1、省略主语 祈使句中主语通常省略；其它省略主语多限于少数现成的说法。
(1) (I) Thank you for your help.
(2) (I) See you tomorrow.
(3) (It) Doesn’t matter.
(4) (I) Beg your pardon
2、省略主谓或主谓语的一部分
(1) (There is) No smoking .
(2) (Is there) Anything wrong ?
(3) (Will you) Have a smoke ?
(4) What/How (do you think) about a cup of tea ?
