--Mr. Li will check our homework this afternoon.  ______ you _______ it?

--Not yet. I'm doing it right now.

A．Do, finish

B．Had, finished

C．will, finish

D．Have, finished

牛创伤性网胃炎时，驱赶上下坡运动，其表现是( )。

A．上坡易下坡难

B．下坡易上坡难

C．上下坡都易

D．上下坡都难

E．不确定