questions about english

1. A dog is an animal.
2. Dogs are animals.

第一句係singular, 而 第二句係寫第一句的plural form.

2007-02-20 15:16:39 補充：
凡係有singular 的常見名詞,字前要加冠詞(article) ie: the, an, a. An 同 a 是 indefinite article, 可以用去連兩個字. 在第一句, dog 和 animal 都係 singular, 所以兩個要冠詞. 例如:That dog is an animalHis dog is an animal等等不過寫plural 時就唔一定有冠詞. 有的時候, 通常是寫那個, 或是數目字. 例如:All dogs are animals.Those dogs are animals.

A dog is an animal .
The dog is an animal .
Dogs are animals .

上述三句都可以表達同一個意思 :
" 狗是動物 " ( 被視為一整體集合 , 即狗這個類別 )

A dog is an animal .
The dog is an animal .
( = Any dog is an animal . )

Dogs are animals .
( = All dogs are animals . )

其實正確答案係:
Dogs are animals.