The teacher is writing a piece of chalk on the blackboard while the students are writing

问题补充：

The teacher is writing a piece of chalk on the blackboard while the students are writing ink in exercise books.

A. with, in

B. in, with

C. in, in

D. with, with

答案：

(答案→)A. with, in

B. in, with

C. in, in

D. with, with

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