Why don’t you your teacher for help when you can’t finish it by yourself ?
A. ask; write
B. to ask; writing
C. ask; writing
D. asking; write
网友回答
A. ask; write
B. to ask; writing
(答案→)C. ask; writing
D. asking; write
解析：why don’t you do sth是固定句型结构意思是你问什么不…表示一种建议；finish doing sth表示完成某事也是固定句型结构。