________he will come to help us is not clear

She’llnever forget her stay there ________ she found her son who had gone missing twoyears before.

下列句式类型不同于其他三项的一项是（　　）

student of Senior Three, he has very little free time _________ he can spend developing his own interest.

Experts are trying to work out a plan to deal with the problems caused by global warming________it is too late.[ ]