4、add / add to / add ... to / add up / add up to

add：加、加起来，常用：add A and B 或add sth. up

　　e.g. If you add two and three, what / how much will you get?

　　 又说、补充说

　　e.g. "I don't trust him any more." He added. = He added that he didn't trust him any more.

add to：增添、增加

　　e.g. His illness added to our worry.

add ... to：把......加进......里

　　e.g. Please add some more sugar to the water.

　　 Add some salt to the soup, and it will be more delicious.

add up：把......加起来

　　e.g. Would you please add these numbers up?

add up to：总计达...... = come to

　　e.g. These numbers add up to 5678.

　　 His debts added up to ten thousand yuan altogether.

5、common / ordinary / usual

common：指"因常见而不足为奇"。

e.g. In the past, cars were rare, but now cars are common.

　　 It is a common sight to see foreigners walking in the street.

ordinary：指"平淡无奇、无特别之处"。

e.g. I don't want to wear this dress to attend this ordinary meeting.

　　 He is one of the ordinary workers in our factory.

usual：指"习惯性的、遵循常规的、一贯如此的"。

e.g. He is reading in his usual chair.

　　 After the flood, everything returned to usual.

常用短语：as usual：与往常一样；than usual：比平常......；as is usual with sb.：某人一贯如此

e.g. As usual, today he got up at 5:30 and prepared breakfast.

But yesterday he got up earlier than usual.

As is usual with him, he failed to do his homework.

常用句型：It is usual (for sb.) to do sth.：（某人）做......是常有的事。

e.g. It is usual for him to be late for school.

6、each other / one another

each other：（通常指两者间的）互相、相互

e.g. The two boys helped each other all the way and they got home finally.

one another：（一般指三者或三者以上的）互相、相互

　　e.g. Students should learn from one another.

区分：one... the other：（一般指两者中的）一个......另一个

e.g. I have two brothers. One is a worker, the other is a doctor.

7、provide / supply：提供、供应

provide：常用句式：provide sb. with sth. = provide sth. for sb.

　　e.g. Our school provides snacks for the students every afternoon.

　　 The power station provides us with cheap electricity.

provide：可以解释为：抚养、瞻养，用：provide for sb.句式。