用if造句

1.I could do it now, if you like.如果你愿意的话，我现在就可以做这事。 2.You can come with us if you want to.如果你愿意可以跟我们一起来。 3.Put your hand up if you need more paper.若有人还要纸，请举手。 4.Call me if you have any problems...