问题
选择题
By the time Jack r
eturned home from England, his son. from college.
A．graduated
B．has graduated
C．had been
D．had graduated
答案
答案：D
考查动词时态，By the time 截止到过去某时间为止做了某事，用过去完成时态。 A是一般过去时；B是现在完成时；C是过去完成进行时。根据句子意思“截止到Jack从英国返家，他的儿子已经大学毕业了。