【正确答案】 D

【答案解析】需要注意的是，在不定式作feel，listen，hear，have，make，let，watch，see，notice，observe，look等感官动词的宾语的补足语时，不定式的符号to必须省略。例如：Thechildren were surprised when the teacher had them close their books unexpectedly．老师突然让他们把书都合上，孩子们感到很惊奇。We can make the liquid nitrogen turn back into agas．我们能使液氮重新变成气体。They felt the atmosphere become increasingly tense．他们感到气氛变得越来越紧张。