题目内容：

请根据句意从方框中选择合适的词，并用其适当形式填空，使句子通顺。

	useful     pollute      two     careful     safe

 

 

1. John always does his homework ______________ in order not to make any mistakes.

2. It’s ______________ to find any excuse when you do something wrong.

3. The factory makes a new type of cars which produces less air ______________.

4. All the victims were saved and taken to ______________.

5. We all know Mother’s Day is on the ______________ Sunday of May.