He sent the letter by air mail _____ it might reach them in good time.A.because B.so as toC.so that D.for

He sent the letter by air mail _____ it might reach them in good time.A.because B.so as toC.so that D.for
He sent the letter by air mail _____ it might reach them in good time.A.because B.so as to
C.so that D.for

He sent the letter by air mail _____ it might reach them in good time.A.because B.so as toC.so that D.for
选C.整句话的意思是他用航空邮件发送这封信以便它能及时送到他们那里.because的意思是“因为”,for的意思之一也是“因为”,两者都可排除.so as to 和so that 的意思都是“以便、为了”,但前者后面跟动词,后者后面接从句,故而只有so that 符合,选C

C

c
从意思上说，是因果关系，采用航空信件，所以能及时到达。排除a和d。
it might reach them in good time是个句子，排除b，因为so as to 后面直接跟名词。

C.so that

A

D