做做下面这两道题，以此巩固一下这个考点。

1.Mike's new DVD player is only about 20 cm ______ 15 cm and weighs______2 kilos.

A.with；in

B. by；about

C.with；for

D. between；over

【答案选B】“长×宽”中的“×”读作by。第二个空可以选择about表示“大约”；或over表示“超过”。

2.I feel that one of my main duties ______ a teacher is to help the students tobecome better learners.

A. for

B. by

C. as

D.with

【答案选C】从句义看，这里谈论的是职责，选用as来表示身份、职业等。