十五

祈使句

祈使句一般用来表示请求，命令，劝说，号召，警告等，在祈侠句中通常省略第二人称主语you，肯定式以动词原形开头，否定式在动词原形前加don't。例如:

Practice the guitar every day.

Don't fight.

为表示礼貌，祈使句中经常在句前或者句末加please。例如:

Let's tell you the way to my house.

选择疑问句

选择疑问句是指说话人提出两种或两种以上情况，问对方选择哪一种，两个选择项用or连接。不能用Yes或No回答。朗读时or前面部分用升调，后面部分用降调。例如:

— Is she tall or short? —She is tall.

—What would you like tea or coffee？—I'd like some tea, please.