根据句意及汉语提示完成下列句子。

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.