1. 我的爷爷过去经常生病，现在由于锻炼非常健康。
    My grandfather _________ _________ be ill, but now he is quite healthy because of exercise.
2. 那个男孩很聪明，他每天自学法语。
    The boy is very clever. He _________ _________ French every day.
3. 动植物需要充足的水分，没有水它们不能生存。
   Plants and animals need _________ _________ water, and they can’t live without it.
4. 对不起，我把你错当成你弟弟了。
    I am very sorry that I _________ you _________ your brother.
5. 这座城市推掉了许多旧房子，同时也建起了相当多的新建筑。
    The city _________ _________ many old buildings and built quite a few new ones.