Question

12. He couldn't speak; he could only mouth several words which sometimes were hard    .

A. understand       B. understood

C. understanding    D. to understand

Answer 1

12.   D考查非谓语动词。句意：他不会说话；他只能喃喃地说几个词，有时很难听懂。解题关键：熟知句型"sb/sth be + adj. +todo"的用法。分析句子结构可知所填空的句子是定语从句，主句为he could only mouth several words ，从句为which sometimes were hard...，故选D。