第1个回答 2013-02-20
forget to do/doing, have sb. do,remember to do/ doing,enjoy doing,be busy doing sth,stop to do/ doing,stop sb. from doing , ask sb. to do,let sb. do, allow sb. to do,be always doing, be good at doing ,be able to do……
第2个回答 2013-02-20
have difficult (in) doing sth.
had better to do sth.
第3个回答 2013-02-20
spend...doing...
try to do