[英文] 英文gammer

do, does, did 基本上有三種用法
1. 做 main verb,
. I do my homework.
He does his homework.

2. 用來做 auxiliary verb (助動詞), 轉否定句子, 問題
Hr does not like chocolate. ~否定句子
Does he like chocolate? ~ 問題

3. 還用來做 emphasis (加強語氣)
I do like chocolate. (do 字在這句子, 用來加強語氣)

Be 可做 main verb 或 auxiliary verb
Be 的 form 有 am, is, are, was, were
1.做 main verb 是做 linking verb (連系動詞)
You are happy.
She is a teacher.

2. 做 auxiliary verb (助動詞), 組成 continuous tense
be + verb -ing
He is doing his homework ~ present continuous tense
She was crying. ~ past continuous tense

present simple tense句子轉否定句子

要知道 subject (主語) 是第一者, 第二者 或 第三者, 同時知道是 singular (單數) 或 plural (複數)

He, She, It, Mr. Lee, girl, dog, teacher, table … (第三者單數)

如果 subject (主語) 是第三者單數, 轉否定句子, 首先要加上 does not, 將原本的 main verb, 轉回 basic form (例如 does 轉回 do, goes 轉回 go)

He does his homework. -.> He does not do his homework.
He likes chocolate. -.> He does not like chocolate. (注意 likes 轉回 like)
Peter does his homework. -.> Peter does not do his homework.
The girl does her homework. -.> The girl does not do her homework.

其他的 first person, second person, third person plural, 只加上 do not

The girls do their homework. -.> The girls do not do their homework.
Girls 是第三者複數

continuous tense 轉否定句子, 比較簡單, 不論第幾者, 只加上 not
I was doing my homework. -.> I was not doing my homework. (past continuous)
He is doing his homework. -.> He is not doing his homework. (present continuous)

使用 linking verb, 轉否定句子, 只加上 not
I am happy. -.> I am not happy
He is a teacher. -.> He is not a teacher.
The girl was happy. -.> The girl was not happy.

小心第三者單數轉去問題 (question)
He does his homework. -.> Does he do his homework?
The girl does her homework. -.> Does the girl do her homework?

You don't like chocolate. = 你不喜歡朱古力 (like 是 verb, 解喜歡)

You aren't like chocolate = 你不似朱古力
(like 是 adjective, 解相似, are 是 linking verb)

2013-12-04 10:20:20 補充：
不是 gammer, 是 grammar

小心 spelling (拼字)

早前我上載了一些錄像在Youtube，解釋一些基本的文法規則，這個錄像正正回答你的問題，希望可以幫到你。

http://www.youtube.com/watch?v=KcLKGqZtXnk

首先假如你問的be=is/are的意思是本體(本身)的意義-即是個人或物件的本質
而不是行為/動作的動詞才會用be的寫法，所以要按句子或寫法表達的意思決定。如果內容是講行為/動作的話差不多一定不會是be.

其中你設問
He usually isn't do his homework.
當中的is/isn"t其實是present continuous tense中的那個is doing的is
所以這句的動詞是do而不是is
這句仍可以改正/改作成為
He usually isn't doing his homework after lunch.變為一句現在進行式的表達那好像你在一直旁觀住他全日的過程而描述一段時間延續中的評語。

另一句
You aren't like chocolate
當然不對，因為like chocolate這like並不是you/主體的本質而是行為。
但英語中仍有一種原始的講/寫法是
I ain't like chocolate.
You ain't like chocolate.
Ain't這個反義原動詞在通俗英語中可以用，但不是正規文法，一般是英語人當中文化不高的人才會講(因為不用理會那些do/does的分別)同時亦可表達對個人(當事人)的本質-意思有點表達:「他就是這樣不xxx」的意思。

你的問題可能類似原自中文思維中
你「係」點/做/想 - 這輔助詞而想像為所有意思都應該係is
但英語文法是動詞主導的，所以留意分辨是動作詞還是本質詞的寫法。

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