第16题: [单项选择]When the engine would not start, the mechanic inspected all the parts to find what was at ______. A. wrong B. trouble C. fault D. difficulty 参考答案:C 答案解析:[解析] at fault是固定搭配,意思是“出故障,出差错”。A.wrong是“错误的”,是形容词,不与at搭配;B.trouble与in搭配;D.difficulty也与in搭配,不与at搭配。