根据所给提示，完成句子。每空一词，含缩略词。

小题1:Chen Ping received an e-mail last Friday. (改为否定句)

Chen Ping                              an e-mail last Friday.

小题2:There are fifty students in our class. (对划线部分提问)

                            students are there in your class?

小题3:I often borrow a dictionary from Bruce. (改为同义句)

Bruce often                his dictionary                me.

小题4:交卷前你应仔细检查。(完成译句)

You should check your answers carefully before you                           your paper.

简单化油器的构造由（）、（）、（）、（）和（）等组成。