Grammar: (1) Perfect Tense (2) Connective
语法：(1) 完成时 (2) 关联词

1．完成时

1．1 现在完成时（Present Perfect Tense）的用法：现在完成时由助动词have （has）+ 动词的过去分词构成。

1) 过去某动作到现在已完成或刚完成，或对现在产生了结果。
I have finished my work.
We have set up many new factories in the last few years.

2) 动作在过去发生但一直延续到现在。
How long have you been in Lanzhou?
Many strange things have happened since I came here

* 现在完成时的时间状语问题。

a) 现在完成时属现在范畴，不能和表示过去的时间状语连用，如 yesterday, last week, two days ago, in 1960…等。
The Second World War began in 1941. √
The Second World War had begun in 1941. ×

b) 现在完成时常和表示不确定的时间副词连用，如already, often, never, ever, always, yet, just … 等。
Have you ever been to the countryside?
The children have already finished eating.

c) 可以和包括现在在内的时间状语连用，如now, today, this month…
Today I have made eleven model planes.
Everyone has expressed his opinion.

1．2 过去完成时（Past Perfect Tense）的用法：由助动词had + 动词的过去分词构成。

1) 表示过去某一动作或时间以前就完成的动作，既"过去的过去"，句中常有for, before,时间短语或时间从句。
By the end of last year, 23 experts had been sent to that area.
He had never gone to a club before he was eighteen years old.

2) 表示由过去某一时间的动作一直延续到过去另一时间，句中常有for, since短语或since引导的从句。
It rained yesterday after it had been dry for many months.
By the time he settled in France, he had visited 29 countries.

1．3 将来完成时（Future Perfect Tense）的用法：表示在将来某一时间以前已经完成的动作。由shall（第一人称）或will（第二、三人称）+ have + 动词的过去分词构成。

By the end of this semester, we shall have learned ten lessons.
When you come tonight at 10 o'clock, I shall have finished the writing.

1．4 过去将来完成时（Future-in-the-past Perfect Tense）的用法：表示在过去某一时间以前已经完成的动作。由should（第一人称）或would（第二、三人称）+ have + 动词的过去分词构成。

I hoped that when we arrived there they would have made everything ready.

2．关联词 （Connective）：有些地方称并列连词（a word or phrase whose function is to link other linguistic units）。其特点是关联词（并列连词）前后的句子成分在语法上是平行的。常用的并列连词有and, as well as, but, yet, however, therefore, so, or, nor, neither…nor…, either…or…, both…and…

It was cold and he had no money to buy food.
It rained heavily last night, but I still went to the theater.
The work is good, yet it could be better.
You must set aside time for work as well as play.
Hurry up, or you will be late.
I never saw him nor heard from him again.
You may write the letter either in ink or in blood.
Both you and me are invited to the party.
The book is due tomorrow. Therefore you must finish it today.
My sister-in-law enjoys pop music. So do I.
He can't speak Italian. Nor can I.
She can swim, play basketball and play piano as well.