167.
M: I thought that computer cost 1,000 dollars.
W: It used to , but the shop owner has lowered the price by 150 dollars.
答案解析：
正确答案为B。根据I thought that computer cost 1,000 dollars.我以为那台电脑要1000美元呢。以及lowered the price by 150 dollars.降了150美元。可知，现在这台电脑的价格为850美元，因此B项正确。

168.
W: Prof. Wang said that the final exam would cover the first nine units.
M: Really? I thought it only included the first five units. Then I must spend the weekend going over the rest of them.
答案解析：
正确答案为A。根据final exam would cover the first nine units.期末考试的内容包括前九个单元的内容。而男子以为it only included the first five units.只包括前五个单元，所以周末going over the rest of them.要复习剩下的内容，即四个单元，因此A项正确。