Question

Mr. and Mrs. Chang have been married _____.

A. when they were twenty years old    B. since twenty years

C. for fifteen years    D. in two months

Answer

C

【解析】

句意：常先生和太太结婚15年了。when they were twenty years old当他们20岁的时候；since twenty years自从二十年；for fifteen years15年了；in two months在两个月之内。句中使用的时态是have been married，现在完成时，这里表示结婚多长时间了，故应用for后跟一段时间，选C。