单项选择题
They are two dollars each but if you buy ten, you get a（）of ten per cent.
A.discount B.recession C.depression D.discharge
单项选择题 Gary has planned to take a tour around the Great Lakes in the coming summer vacation and（） great pleasure from the visit.
单项选择题 The survival of civilization, as we know, is（）threat.
单项选择题 The wise man exercises（）in his behavior and enjoyments.
