— I tried many times, but I still failed to complete the experiment.  

— Cheer up. _______ and the problem will be solved.   [ ]

A. If have a little effort

B. Having a little effort  

C. If you have a bit effort

D. A bit more effort

塞因塞用不适用于（）。

A．脾虚腹胀

B．血虚便秘

C．血枯经闭

D．肾虚尿闭

E．血瘀经闭