If water freezes, it ...........................(expand).
expands
When we recycle one tone of glass, we...........(save) 315 kg of CO2.
save
If it rains,.............( take) an umbrella!
take
The Arctic ocean becomes almost completely covered in ice when it............(be) winter.
is
When we heat water to 100C, it .....(boil)
boils
You...............(save) money and ............(help) environment if you carpool.
will save, help
When Arctic ice caps and glaciersmelt, sea levels..........(rise)
rise
If you go through the Sahara desert by foot, it .............(take) you nearly 50 days to cross it.
will take
When you are cold, you ...........(should dress) more warmly.
should dress
You ............( dehydrate) if you .............(not drink) enough water.
will dehydrate, don't drink
If people .........(use) fluorescent light bulbs, they .....(help) save energy.
use, will help
We............(slow down) global warming if we all..........(act) now.
can slow down, act
If deforestation ............(continue), wildlife and many plants............(become) extinct.
continues, will become
If you ..........(have) a picnic, you.......(clean up) before you leave.
have, must/should clean up
When you........... (be) in the nature reserve, you...........(pick) flowers.
are, mustn't pick
