1)　and 与or

　判断改错：

　(错) They sat down and talk about something.

　(错) They started to dance and sang.

　(错) I saw two men sitting behind and whisper there.

　(对) They sat down and talked about something.

　(对) They started to dance and sing.

　(对)I saw two men sitting behind and whispering there.

解析： 

　 第一句： and 连接两个并列的谓语，所以 talk 应改为 talked。

　 第二句：and 连接两个并列的动词不定式，第二个不定式往往省略to，因此sang 应改为 sing。

　 第三句：and 连接感观动词saw 后面的用作的宾补的两个并列分词结构，因此whisper应改为whispering。

注意：and 还可以和祈使句或名词词组连用表示条件。（or也有此用法）

　　 Make up your mind， and you’ll get the chance.

　 = If you make up your mind， you’ll get the chance.

　　 One more effort， and you’ll succeed.

　 = If you make one more effort， you’ll succeed.

2)　both …and　两者都

　She plays (both) the piano and the guitar.

3)　not only…but (also)， as well as不但…而且）

　　　She plays not only the piano， but (also) the guitar.