If____________ , the polluted air can result in deadly diseases or even death.
Some children want to challenge themselves by learning a language different from their parents speak at home.
______, and everything will be all right.
In my opinion , the thief is likely to come , please look _____ for him .
When I graduate from this famous university, I’ll _______ what I have learned to everyday life.
. --- I usually go there by bus. It is very crowded. --- _______ there by train? It’s fast and cheap.