1、復(fù)雜句(Complex Sentences)，主句+從句。

主句（獨(dú)立存在）+從句（不是句子，不能單獨(dú)使用）=復(fù)雜句

The boy who lived next door went fishing last weeked.

Skipping merrily down the road, Sally waved at her friends.

Though he was late for class, he walked slowly down the hall.

After running a mile, Barry sat down exhausted.

He was already full and needed only a glass of water. (不是復(fù)雜句)

2、復(fù)合句（Compoud Sentences），兩個(gè)主句 + 一個(gè)連接詞。

John is taking seven classes this semester, so he was no time to play soccer.

He was an excellent swimmer, and his friend was a great distance runner.

3、復(fù)合復(fù)雜句（Compoud Complex Sentences）。復(fù)合句+復(fù)雜句。

John was a triathlete who trained everyday, but he was still unable to finish the Iron Man Triathon.

Though John trained everyday, he was unable to finish the Iron Man Triathon.(不是復(fù)合復(fù)雜句)

When David arrives in the afternoon, we will be able to eat out, but we will not have enough time to go shopping.

David, who is arriving this afternoon, will not have enough time to go shopping.(不是復(fù)合復(fù)雜句)

4、逗號拼接謬誤（Comma Splice）。用逗號來分離兩個(gè)主句的時(shí)候容易犯錯。一般情況下，用逗號+連接詞，分號或者句號其中一個(gè)。

Mike studied diligently each night，he was able to get stright A's.(此處逗號之后沒有連接詞，此句錯誤，正確應(yīng)為 Mike studied diligently each night，so he was able to get stright A's. )

Though he practiced piano two hourse each day, he still could not master the sonata, it was so difficult. (第二個(gè)逗號是錯誤的，缺少連接詞)