He didn't what I read because his mind was on something else.A. hold onB. catch onC. take

问题补充：

He didn what I read because his mind was on something else.

A. hold on

B. catch on

C. take in

D. get over

答案：

A. hold on

B. catch on

(答案→)C. take in

D. get over

解析：take in(=understand)理解。参阅Ⅲ。173注释。hold on(打电话时)不要挂断；catch on明白（作不及物动词用），catch on to懂得，明白（作及物动词用）；get over克服。