完成句子。
1. The two countries were then ______ ______ (交战). People lived a hard life.
2. The letters PLA ______ _______ (代表) the People's Liberation Army.
3. To be a good learner, you must ______ ______ ______ ______ (充分利用) the library books,
newspapers and magazines.
4. They were both punished ______ ______ ______ ______ (由于……的结果) smoking.
5. He likes to _______ _______ _______ (拿……开玩笑) me because we are friends.
