旅行社安排的住宿饭店低于合同约定的等级档次,旅行社应退还旅游者所付房费与实际房费的差额,并赔偿差额( )的违约金。
A.10%
B.20%
C.30%
D.50%
参考答案:B
He regretted()too much time on computer game.
A. to cost
B. costing
C. to spend
D. spending
地球上约有()种海洋生物。
A.10万
B.20万
C.30万
D.40万