单项选择题
People appreciate（）with him because he has a good sense of humor.
A.working B.to have worked C.to work D.having worked
单项选择题 Nobody knows how long and how seriously the shakiness（不稳定） of big businesses will （） down the economy.
单项选择题 I tried very hard to persuade him to join our group but I met with a flat（）
单项选择题 Our department（）courses in several foreign languages.
