3. 解析:选A。句意为:海伦总是帮助她妈妈，即使上学占去了她一天中的大部分时间。take up占去(时间、空间)；make up编造，弥补；save up省下，节省；put up挂起，举起。

2. 解析:选D。offer此处意为“出价”，指他给我们的房子出价是15万美元。其他三个词均无此意。

5. You should spend two hours on average every day taking exercise.

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4. Your plan is reasonable in theory but not practical in reality.

3. Don’t take it for granted that your mom gets up early every day to prepare breakfast for you.

2. He likes this song in particular because his mother used to sing it.

5. developed

B. 1. effect2. influence3. effect

7. salary　 8. profound　 9. requirement　 10. available