1 . She sings as if she was a p________(职业的，专业的) singer. （根据中英文提示填空）

2 . He said he would go over the g________(语法) lesson once again. （根据中英文提示填空）

3 . It’s not fair to c________(比较) yourself to others, as everyone has their own unique strengths and weaknesses. （根据中英文提示填空）

4 . All of a s________(突然), the lights went out and the room was plunged into darkness. （根据中英文提示填空）