on account of 介词短语

Because 从属连词"因为"表示所叙述的理由是本局的重点

as/since 从属连词"因为"表示理由是已知的， 而理由以外才是叙述的重点for 并列连词，不用于句首，置于第一分句之后，补充理由；第一分句表示推测时，用 for说明推测的依据。

therefore 副词 "因此"

so 并列连词 "因此"

The accident was ____ his careless driving.

due to B. because

C. because of D. Both A and C

Key: D

2. I became addicted to cigarettes.

addict vt. (1)使沉溺; 嗜好(2)使...成瘾, 热衷于

addict oneself to 沉溺于, 醉心于

be addicted to 嗜好, 热衷

He became addicted to the drug. 他上了毒瘾。

The children are addicted to computer games.

(喻)孩子们对计算机游戏上了瘾。

addict n. (1) 上了瘾的人

film addict 电影迷 (2)吸毒者

This means that after a while your body becomes accustomed to having

nicotine in it...

accustom v. vt. 使习惯于

be /get / become accustomed to 习惯于；适应于

accustom +n. /oneself +to 使自己习惯/适应于

其中to 为 介词

The boy has become accustomed to speaking English in public.

那孩子已经习惯于在公众面前说英语了。

My eyes soon grew accustomed to the darkness.

我的眼睛很快适应了黑暗 。

They had to accustom themselves to the hot weather.

他们不得不使自己习惯于炎热的天气。

4. I knew it was time to quit smoking.

quit 动词，过去式和过去分词均为quit，现在分词为quitting，

①接动词-ing形式，"停止做"

I wish you'd quit complaining.

② 辞职, 离开

His father quit because of ill health.

He has to quit school because he can't afford the education.

知识拓展

只能用动词的 -ing形式做宾语的动词和短语还有

miss, admit, avoid, acknowledge, consider, appreciate, delay, enjoy, escape, deny, fancy, favor, finish, mind, postpone, recall, practice, excuse, imagine, include, keep, mind, resent, resist , suggest, risk, resume, involve, justify, permit, prevent, put