The repairperson could not find the specific problem_________

单选题The repairperson could not find the specific problem__________ had caused the computer to crash。

A．How
B．whom
C．what
D．that

参考答案D

解析:通过分析句子结构，空格前为主语+动词+宾语的结构，因此空格以后的都必须为修饰先行词problem的关系代词从句。

单选题 According to the sales director, Ms.Elms is__________ to one of our subsidiaries to collaborate with its sales team,

A．delivering
B．visiting
C．transferring
D．replacing

单选题 We need to conduct extensive background research on the firms from__________ we received bids。

A．which
B．where
C．that
D．when

单选题 The director decided to delegate some of the work to a subcontractor after his employees __________help with the project。

A．Inquired
B．requested
C．asked
D．insisted