Please be quiet in the library.（请在图书馆里保持安静。）

Don't forget to take your umbrella with you when you leave the house.（出门时别忘了带伞。）

Make sure you finish your homework before you go out to play.（确保你出去玩之前完成作业。）

Listen carefully to the teacher's explanation.（仔细听老师的解释。）

Help me carry these heavy boxes to the storage room.（帮我把这些重箱子搬到储藏室。）

Please clean up the mess in the kitchen.（请把厨房里的混乱清理干净。）

Be careful when crossing the street, the traffic is very busy.（过马路时小心，交通很繁忙。）

Let's plan our trip to the mountains next weekend.（让我们下周末计划去爬山。）

Don't be late for the meeting, it's important.（不要迟到开会，这很重要。）

Take care of your health and stay healthy.（照顾好自己，保持健康。）

这些例句涵盖了祈使句的不同用法，包括请求、命令、建议、警告等。希望这些例子对你有所帮助。