理工类辅导资料：主语 系动词 表语
It is important to learn English grammar.
It was important to learn Russin grammar.
It will be important to learn Russin grammar.
It is important that we learn English.
It was important that we learnt Russin grammar.
It will be important that we learn Russin grammar[Page] 所谓“体”，是指动作在过去、现在和将来三个不同时间所处的状态。即：常态、进行或完成。那么就有了过去、现在和将来的常态、过去、现在和将来的进行、过去、现在和将来的完成。注意，“体”所表达的主要是对动作的描述，就“主—系—表”结构而言，因为只用来表达静态的事物，所以不存在进行和完成的问题。我们通过以上例句做进一步的说明：
1． 主语 系动词 表语
1）. Tom is a college student.
Tom was a college student.
Tom has a college student.
2 ）It is sunny today.
It was sunny yesterday.
It has sunny .
2. S V O 主语 谓语 宾语
Tom studies English now.
Tom is studying English now.
Tom was studying English at 8：00 yesterday.
Tom has studied English.
3. S V 主语 谓语
Tom studies hard.
Tom is studiying hard.
Tom was studying hard before.
Tom has studied hard
4. S V Oi Od 主语 谓语 间接宾语 直接宾语
Tom gives me a book.
Tom is giving me a book.
Tom was giving me a book at that time.
Tom gave me a book.
Tom has given me a book.