New words：

role [rəul] n. 作用；角色
The Panama Canal [ˈpænəmɑː kəˈnæl] 巴拿马运河
transportation [ˌtrænspərˈteɪʃ(ə)n] n.运输

Sample Sentences：

He denied any role in the robbery.
She acted as a minor role in the play.
She played the leading role in the school play.
The Panama Canal has played a very important role in transportation.

canal [kə'næl] n.运河；沟渠；管

New words：

average ['ævəridʒ]
n.平均水平；平均数；一般水准
adj.平均的；典型的；正常的；普通的
v.平均为；计算出…的平均数

Sample Sentences：

The average of 4,6 and 8 is 6.
If you average 4, 5 and 9, you get 6.
The average age of the boys in this class is fifteen.
There was nothing special about the meal; it was average.

New words：

rate [reit] n. 率；速度；比率；价格

Sample Sentences：

We drove at a steady rate.
The school has a 90% pass rate.
What's the rate for a single room?
House prices are rising at a higher rate than before.
Most people walk at an average rate of 5 kilometres an hour.

average ['ævəridʒ]
n.平均水平；平均数；一般水准
adj.平均的；典型的；正常的；普通的

New words：

crime [kraim] n. 罪；罪行；犯罪活动；罪过

Sample Sentences：

The crime rate is rising.
It's a crime to waste food.
When will the police solve the crime?
Many people believe that prison isn't a cure for crime.

rate [reit] n. 率；速度；比率；价格

New words：

vehicle [ˈviːəkl] n. 车辆；交通工具；载体；运载工具

Sample Sentences：

Air is the vehicle of sound.
Are you the driver of this vehicle?
No vehicles are permitted into the park.
Language is the vehicle of human thought.