是用动名词还是动词不定式working(to work) out the math problem like this题目是Did you have difficulty in study?Yes,____ out the math problem like this.C.working D.to work1,为什么不能用动词不定式2.动词不定式放句首也是作主语吗?3.如何判断一个句子中,动名词放句首,还是动词不定式放句首

是用动名词还是动词不定式working(to work) out the math problem like this
题目是Did you have difficulty in study?
Yes,____ out the math problem like this.
C.working D.to work
1,为什么不能用动词不定式
2.动词不定式放句首也是作主语吗?
3.如何判断一个句子中,动名词放句首,还是动词不定式放句首