分类：教育/科学-外语学习-英语考试
问题：高一英语Themotherdidallshecould_____ 
The mother did all she could______her son .A to help   B help     to help    D  helps 那个正确呢?为什么(麻烦,详细点)?
回答：C
do all (that) one can/could (do) to do 
= do what one can/could (do) to do
to do表目的