The boss refused to sell the car for he thought was not satisfactory. A. thatB. which C.

问题补充：

The boss refused to sell the car for he thought was not satisfactory.

A. that

B. which

C. how

D. what

答案：

A. that

B. which

C. how

(答案→)D. what

解析：what he thought这是一个主语从句，what在从句中宾语，that，which 和how这三个都不能作宾语，故选D。for这里是并列连词，表原因。句意：老板拒绝卖那辆车，因为他想的那些事不是满意的。