III. Choose the best answer to complete the sentences.

1. America says it ____________ until other countries ____________ more action.

A. won’t act - took                                       B. won’t act – take  

C. doesn’t act - will take                             D. acts - don’t take

2. ____________ you buy and use a plastic bag, ask yourself if you really need it.

A. Before                   B. When                     C. While                     D. After

3. ____________ the arrival of humans on Earth, species became extinct naturally.

A. Before                   B. Since                      C. After                      D. As soon as

4. ____________ my little cousin saw the tiger in the cage, he cried out.

A. Before                   B. Since                      C. When                     D. Until

5. As soon as we ____________ risks of climate change, we all ____________ together to fight against them.

A. realize - worked  B. realized - worked            C. realized - work     D. will realize – work

6. ____________ I get to school, I will show you my writing about the habitat of polar bear.

A. As soon as                        B. While                     C. Until                      D. Till

7. __________ fossil fuels are burnt, they release large amounts of carbon dioxide into the air.

A. Till                         B. Until                                  C. Before                   D. When

8. Most species don’t receive protection ____________ their populations reduce to nearly zero.

A. as                           B. when                      C. before                    D. until