The zoo keepers is worried because the number of visitors __ smallerand smaller.

Had they known what was coming next, they　　　second thoughts.

When the passengers’ (乘客) families heard the bad news, they were _____ to stay calm.

you have a good time in the US during theGolden Week Holiday — ______ Due to the temporary governmentshutdown, a lot of national parks were closed.

What will global warming(全球变暖) bring us Scientists have given us a clear list.