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．

1、1．used to             2．teaches himself             3．plenty of         

4．mistook，for    5．pulled down