In our class ,when the bell rang and the teacher closed his book ,it was a ________for everyone to stand up .
— People should spare no efforts to protect the environment. — ________. Air pollution does harm to our health.
Our responsibility is weightier than ______Mount Tai, and our road ahead is _______ long one.
Never before______ such a wonderful park, ______ I'd like to pay a visit again.
impresses me most isChinese students are well organized and disciplined. We should learn from them.
It be the vocabulary that caused you the problem in the exercise because you know a lot of words.