（一）第一種類型：“爆破音+爆破音”型

6個爆破音中的任意兩個相連時，前一個爆破音會失去爆破，即由相應的發音器官做好發音的姿勢，不爆破，稍作停頓後就發後面的音。

例：

The girl in the re(d) coat was on a bla(ck) bike.

The bi(g) bus from the fa(c)tory is full of people.

Wha(t) time does he get up every morning?

This is an ol(d) pi(c)ture of a bi(g) car.

The ol(d) do(c)tor has a ca(t)，too.

We're going to work on a farm nex(t) Tuesday.

(二）第二種類型：“爆破音+其他輔音”型

1、爆破音+ [t∫] [ð]：爆破音不完全爆破，即形成阻礙，稍作停頓，不爆破。例：

great changes

good jobs

that child

grandchild

2、 [t] [d]+舌邊音 [l]：爆破音在單詞或短語中形成不完全爆破。例：

at last

good luck

straight line

would like to

a bit louder

friendly

mostly

3、[t] [d]+鼻音 [m] [n] ：爆破音在單詞或短語中形成阻礙，不完全爆破。例：

good morning

good news

start now

midnight

just now

（三）第三種類型：動詞否定式的縮寫形式，結尾的t不發音。例：

He mustn't do it.

You needn't pay for it.

I wouldn't let him go.

You don't know him.

Mary shouldn't call him at work.

1、外殼變形、有裂紋、開焊。

2、螺栓不全、鬆動、缺少彈簧墊圈。

3、外殼內外有鏽皮脫落。