英語句子的基本結(jié)構(gòu)(2)
英語文法的規(guī)則(5)：在不定詞“to”的后面，必須用原形動(dòng)詞
英文中的動(dòng)詞，是會(huì)變化的，以have為例，第一人稱和第三人就不同：
I have a dog.
He has a dog.
如果是過去式，動(dòng)詞又要變化。have的過去式是had，不論第幾人稱，一概都要用had。幾乎每一個(gè)英文動(dòng)詞的過去式都有變化，以下是幾個(gè)例子：
go went come came eat ate play played swim swam
不論那一個(gè)動(dòng)詞，都有一個(gè)原形動(dòng)詞，一切都是從這個(gè)原形動(dòng)詞變出來的，像go、drink、have、walk、love、like等等都是原形動(dòng)詞。
如果我們有必要要用不定詞to，就必須用原形動(dòng)詞，例如to go、to drink、to have，都是正確的，*to went;*to drank;*to loved等等都是錯(cuò)的。
英文中有一個(gè)動(dòng)詞最為麻煩，那就是am、are、is、was、were等等，翻譯成中文，這都是，而這些動(dòng)詞的來源都是be，所以我們說這些動(dòng)詞都是verb to be。
以下的句子都用上了〝be〞
I want to be a teacher.
He wants to be a good father.
They all love to be rich.
No one likes to be poor.
英語文法的規(guī)則(6)：英文中有所謂的助動(dòng)詞。必須注意
英文中有很多動(dòng)詞都是助動(dòng)詞，在規(guī)則(4)中，我們說在絕大多數(shù)的否定語句中，必須用助動(dòng)詞do或did。Do是原形動(dòng)詞，did 和does都是do的變形。
除了do是助動(dòng)詞以外，can、may、might、will、would、must也都是助動(dòng)詞。
以上所提到的助動(dòng)詞，都有一個(gè)共同的特色，那就是這些助動(dòng)詞后的動(dòng)詞必須是原形動(dòng)詞，以下的句子都是正確的：
He can swim.
He does not swim.
I do not speak English.
You must walk to work every day.
I did not work yesterday.
You may leave now.
I will go to Taipei tomorrow.
以下的句子都是錯(cuò)的：
* I did not went.
* He does not goes to work.
* You must walked to work.
除了以上的助動(dòng)詞以外，還有一個(gè)非常特殊的助動(dòng)詞，那就是have，在這個(gè)助動(dòng)詞的后面，動(dòng)詞絕對不能用原形動(dòng)詞，以下是用這個(gè)助動(dòng)詞的例子：
I have been to England.
I have slept all day.
I have studied English since I was a child.
been、slept 和studied都是過去分詞(past participle)，以下的句子也都是現(xiàn)在完成式，我們后討論完成式的時(shí)候，會(huì)將這些解釋清楚的。
英語文法的規(guī)則(7)：英文問句要有助動(dòng)詞
我們先看看以下的英文句子，這些都是錯(cuò)的：
* How many books you wrote?
* How many sons you have?
正確的句子是：
Why do you drink so much water?
How many books did you write?
How many sons do you have?
絕大多數(shù)的英文問句子是一定要有助動(dòng)詞，以下全是正確的英文問句，你可以看出每一句的助動(dòng)詞嗎?
Do you love me?
Did you go to school yesterday?
How many books do you have?
How much money does he have?
Why don't you go back home?
Do you like to swim?
Can you play violin?
Will you go home tomorrow?
Would you give me a call?
當(dāng)然啦，一旦動(dòng)詞是verb to be，我們又不需要助動(dòng)詞了，以下都是正確的英文問句：
Are you a teacher?
Is he a student?
Is Mr. Chang your father?
Were your mother and father in England last year?