which layers of the Skin are burned。【教材P34】

　　1. unless假如不；除非；引导条件状语从句

Remove clothing using scissors if necessary__________【除非衣服粘贴在烧伤面上】.【教材P34】

　　2. be doing...when...正在做......这时......

John__________【正在学习】in his room____________【这时】he heard screaming 【教材P38.]

4.there's no doubt that...毫无疑问....

___________【毫无疑问】john's quick thinking and the first aid skills he learned at school saved MS slade's life【教材P38.】