旋涡泵叶片采用（）。
A．前弯
B．后弯
C．径向
D．三种都有
参考答案：D
—Guess, how much does it cost?
—I think it costs 15 and 20 dollars. [ ]
A. from
B. between
C. among
D. with
—Excuse me. Could you tell me _______?
—Yes, There is a video shop next to the tall building. [ ]
A. where can I buy some CDs
B. where I can buy some CDs
C. when can I buy some CDs
D. when I can buy some CDs
