I.词语辨析：

1、in order to / so as to：都引导目的状语，"为了......、这样就......"。

in order to：引导的目的状语可放于句首、句后，可简写成"to..."。

e.g. In order to study English well, we will have a talk on "How to study English".

He got up early (in order) to catch the first bus.

so as to：引导的状语只能放于句后，也可简写成"to..."。

e.g. He moved to the front (so as) to hear clearly.

c.f. so ... as to...：如此......以至......

e.g. Would you be so kind as to help me with my maths problems?

2、discover / invent / find / find out

discover："发现"本来就存在的、以前未被发现的事物或未为人所知的东西。

e.g. It is Columbus that discovered the America in 1492.

After years of hard work, he discovered the truth in the end.

invent："发明"原来不存在的事物或方法，有时也可指"虚构、捏造"。

e.g. Bell is generally considered to have invented the telephone.

The story is very moving, but it is invented.

find：指无意或偶然发现、找到；

e.g. I found this wallet on my way home.

He found some new words when reading the book.

find out：指有意的通过努力、克服困难找出事物的真相。

e.g. Would you please find out what is on at the cinema today?

3、reach / get to / arrive

reach：vt. 到达，后接地方名

e.g. Soon our car reached the foot of the mountain and we began to climb it.

get to：多用于口语，后接名词；当后接副词时，"to"不用。

e.g. By the time we got to the top of the mountain, she had got home.

arrive：vi. "到达"，当后接地名时，要用介词：in 或at, 大地方用in， 小地方用at。

e.g. Has the plane arrived?

The train arrived at the station at mid-night.

She arrived in Wuhan in 2003 and has lived there since then.

4、holiday / vacation

holiday：指时间较短的"节日、假日"，词义来源于宗教，是普通用词，e.g. be on holiday， go to a place for holiday。当指多天的节假日时，可用复数 holidays， e.g. the summer holidays。

e.g. Sunday is a holiday and New Year's Day is also a holiday.

We had some holidays for the National Day celebration

vacation：指时间较长的"假期、休假"，可以说：be on vacation。

e.g. The summer vacation / holidays is / are long but interesting.

We had a vacation of twenty holidays in the Spring Festival.