He didn't what I read because his mind was on something else.
A. hold on
B. catch on
C. take in
D. get over
网友回答
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。