Inspired by Thai rooftop solar heaters, William Janssen built the Desolenator: a portable, wheeled, solar-powered unit that turns sea, river or rain water into 15 litres of drinking water a day. With water stress spreading and desalination plants too costly for many countries, it's aimed at poor households (via microfinance) and niche Western users, as a social venture rather than a profit machine.
The headings (14-20) take one section each, A to G, and three of the ten headings are left over. The summary (21-26) is all in C.
Matching headings (i-x)
Questions 14-20
How to attack this block: Follow the logic of each section. A goes from idea to product, B covers the many water sources, and C explains what makes the device different (sunlight only). D gives the scale of water shortage, E the range of customers, and F says profit isn't the main goal. G covers funding raised so far. The unused headings (an unexpected benefit, production problems, a warm welcome) describe nothing in the text.
Question 14
Answer: iiiSection A
Which heading sums up Section A?
Two decades later Janssen developed that basic idea he saw in Southeast Asia into a portable device that uses the power from the sun to purify water.
Question says → Passage says
initial inspirationwas impressed with the basic rooftop solar heating systems / that basic idea he saw in Southeast Asia
to new productdeveloped… into a portable device
Why: Section A tells a short story in two steps: Janssen sees solar water heaters in Thailand, then, twenty years later, turns that idea into the Desolenator. That's heading iii, from inspiration to product.
The trap: Heading v might come to mind because A mentions the sun's power, but A doesn't compare the device with anything. Its differences from alternatives are explained in C.
Question 15
Answer: viSection B, first paragraph
Which heading sums up Section B?
a mobile desalination unit that can take water from different places, such as the sea, rivers, boreholes and rain, and purify it for human consumption
Question says → Passage says
Cleaning waterpurify it for human consumption
from a range of sourcestake water from different places, such as the sea, rivers, boreholes and rain
Why: The main idea is the list of places the water can come from (sea, rivers, boreholes, rain) and the regions where that matters, such as places with polluted groundwater or only seawater. That's heading vi.
The trap: B's second paragraph explains how Janssen saw the need in the UAE, which looks like more inspiration (iii). But that's a supporting detail. The section's focus is the variety of water sources.
Question 16
Answer: vSection C, second sentence
Which heading sums up Section C?
Its main selling point is that unlike standard desalination techniques, it doesn't require a generated power supply: just sunlight.
Question says → Passage says
What makes the device differentIts main selling point is that unlike
from alternativesstandard desalination techniques
Why: 'Main selling point' and 'unlike standard desalination techniques' tell you what sets the Desolenator apart. The rest of C describes the parts that make it special: wheels, the thin film, the simple filter, the screen. Heading v.
The trap: Most of C is a step-by-step description of how the device works, so it's easy to go looking for a 'how it works' heading. There isn't one, and the 'different from alternatives' sentence is the frame for everything else.
Question 17
Answer: xSection D, first two sentences
Which heading sums up Section D?
at least two-thirds of the world's population lives with severe water scarcity for at least a month every year
Question says → Passage says
The number of peopletwo-thirds of the world's population / half of the world's population
affected by water shortageslives with severe water scarcity / will be living with water stress
Why: D opens with two big figures, two-thirds of people facing scarcity now and half facing water stress by 2030. Scarcity and stress are both 'water shortages', so heading x.
The trap: Heading i (finance) tempts because the second half of D is all about money. But that's poorer countries lacking money for desalination plants, not the company getting funding.
Question 18
Answer: ivSection E, first sentence
Which heading sums up Section E?
The device is aimed at a wide variety of users - from homeowners in the developing world who do not have a constant supply of water to people living off the grid
Question says → Passage says
The range of potential customersa wide variety of users
for the deviceThe device is aimed at
Why: The first sentence states the topic and the rest fills it in: homeowners in developing countries, microfinance buyers, middle-income homes that lease, and niche users in the West such as campers, boat owners and the military. Heading iv.
The trap: Heading ix ('A warm welcome') might seem to fit the first commercial versions in India. But they're only 'expected' after field tests, so there's no reaction to report yet.
Question 19
Answer: viiiSection F, Janssen's quote
Which heading sums up Section F?
'We are a venture with a social mission… We do realise, though, that to be a viable company there is a bottom line to keep in mind,'
Question says → Passage says
not the primary goalWe are a venture with a social mission
Profita bottom line to keep in mind
Why: Janssen puts the social mission first and the humanitarian sector as the main market. The 'bottom line' (profit) comes second, with 'though'. So profit matters, but it isn't the main aim: heading viii.
The trap: F opens with prices, so heading i (finance) can look right. But prices are what customers pay; the section's point is the company's priorities.
Question 20
Answer: iSection G, second sentence
Which heading sums up Section G?
It has raised £340,000 in funding so far.
Question says → Passage says
Getting the financeraised £340,000 in funding
for productionaims to be selling 1,000 units a month
Why: 'Raised… in funding' is getting finance, and the sales target of 1,000 units a month shows what that money is for. Heading i.
The trap: Heading vii (production difficulties) uses the word 'production', but G mentions no problems at all. Its plans are confident.
Summary completion (ONE WORD ONLY)
Questions 21-26
How to attack this block: C walks through the device in order: what makes it portable, the thin layer water forms over the panel, what traps particles, what comes out of the second tube, what the screen shows, and what the company provides when needed. All six are nouns taken directly from C.
Question 21
Answer: wheelsSection C, fourth sentence
What feature lets the device be used in different places?
It measures 120cm by 90cm, and is easy to transport, thanks to its two wheels.
Question says → Passage says
can be used in different locationsis easy to transport
as it hasthanks to its
Why: 'Thanks to' gives the reason, and the summary's 'as it has' does the same job. The gap needs a plural noun after 'has': 'wheels'.
The trap: 'Two wheels' is two words, and the limit is ONE WORD ONLY. The size (120cm by 90cm) is nearby, but it isn't what makes it mobile.
Question 22
Answer: filmSection C, fifth sentence
In what form does the water flow over the solar panel?
Water enters through a pipe, and flows as a thin film between a sheet of double glazing and the surface of a solar panel
Question says → Passage says
Water is fed into a pipeWater enters through a pipe
a ___ of water flows over a solar panelflows as a thin film
Why: The summary follows this sentence step by step. 'A ___ of water' needs a singular noun, and the passage says the water flows 'as a thin film'.
The trap: 'Sheet' fits 'a sheet of water' perfectly in everyday English, which makes it a strong trap. But in the passage the sheet is made of double glazing, not water.
Question 23
Answer: filterSection C, middle
What catches the particles in the water?
The device has a very simple filter to trap particles, and this can easily be shaken to remove them.
Question says → Passage says
are caught into trap
Any particlesparticles
Why: 'Caught' is a synonym of 'trap', and what traps them is the 'filter'. The gap follows 'a', so a singular noun.
The trap: 'Boiler' is the step just before in the summary, but that's where water becomes steam, not where particles are caught.
Question 24
Answer: wasteSection C, second-to-last sentence
What comes out through the second tube?
There are two tubes for liquid coming out: one for the waste - salt from seawater, fluoride, etc. - and another for the distilled water.
Question says → Passage says
The purified water comes out through one tubeanother for the distilled water
all types ofsalt from seawater, fluoride, etc.
Why: The two tubes are for distilled water and for waste. 'All types of' covers the passage's list of salt, fluoride and so on. The word that names them all is 'waste'.
The trap: 'Salt' is just one example in the list, so it doesn't fit 'all types of'.
Question 25
Answer: performanceSection C, last sentence
What does the screen display?
The performance of the unit is shown on an LCD screen and transmitted to the company
Question says → Passage says
A screen displaysis shown on an LCD screen
the ___ of the deviceThe performance of the unit
Why: The summary turns the passive into an active: 'is shown on a screen' becomes 'a screen displays'. 'Of the device' = 'of the unit', so the noun is 'performance'.
The trap: Don't write 'unit'. 'The unit of the device' makes no sense, since the unit is the device.
Question 26
Answer: servicingSection C, last sentence
What does the company provide when the device needs it?
transmitted to the company which provides servicing when necessary
Question says → Passage says
when the Desolenator requireswhen necessary
so that they knowtransmitted to the company
Why: The company gets the data so it can provide 'servicing when necessary'. 'Requires ___' needs a noun, and 'servicing' is the one in the passage.
The trap: 'Maintenance' means much the same, but in the passage it's in D and describes big desalination plants. The summary follows C, and C's word is 'servicing'. Copy it exactly.
v. C's 'main selling point' is that it needs no generated power supply, only sunlight, which is what sets it apart from alternatives. It isn't about the range of water sources (B).
Water flows 'as a thin film' between the glazing and the panel, so the answer is 'film'.
Words from this passage worth keeping
purify(A)
make clean by removing harmful substances
boreholes(B)
deep narrow holes dug in the ground to reach water
carbon footprint(B)
the amount of carbon dioxide produced by an activity
selling point(C)
a feature that makes people want to buy something
scarcity(D)
a situation where there isn't enough of something
off the grid(E)
not connected to public electricity or water supplies
niche markets(E)
small, specialised groups of customers
bottom line(F)
the need to make a profit
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The full Cambridge 15 Test 3 reading paper: all three passages, 60 minutes, marked the second you finish with a review of every answer. Already done it? Take it again and see if the same traps still get you.
Cambridge IELTS 15, Test 3, Reading Passage 2. The passage and questions belong to Cambridge University Press and are not reproduced here. We quote short extracts only as evidence for our own commentary, and the answers are published for self-marking. Get the book for the full text, or sit the test on Langujet.
