He ______be lazy, but he can work hard when he feels like it．

The school rules state that no child _____ out of the school, unless accompanied by an adult. 

My English teacher was angry           Tom. 

It ________be the vocabulary that caused you the problem in the exercise because you know a lot of words.                                                  

—May I smoke here，please?—I am afraid you           ．This is a non-smoking area．