1.Things like that is happening everyday.(强调每天都在发生 ）
2.-- Excue me,look at the sign:No smoking.
--Sorry,I didn't see it.(指刚才没看见)
3.I met Lily yesterday,but I forgot to ask her for her number.(forget to do表示忘记要干的事情,跟forget doing 表示忘记曾经做过的事情,此处应该用不定式)
4.Then I put the lemon juice into the salad and began to eat it.(begin 后跟不定式或动名词,这里也可以用eating)第一应该用are happening。先行词是things!