问题详情：
![---Itriedmanytimes,butIstillfailedtocompletetheexperime...]( "---Itriedmanytimes,butIstillfailedtocompletetheexperime...")
--- 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
【回答】
D
知识点：固定句型
题型：选择题
