Signs carry messages. For example, a sign at the bus stop helps you to know    小题1: (哪一个) bus to take. A sign on the wall of your school helps you find the    小题2: (图书馆). Signs through doors tell you where to go in or out.    小题3:  (假如) you see the sign “No photography”, you can’t take    小题4:  (照片). When you find the sign “ Danger”, you must be    小题5:  (小心的). If you want to cross the road, you should    小题6:  (等候) for the green light at the crossing. When you visit a museum and see a sign “Keep quiet”, you aren’t    小题7:  (允许) to speak loudly. Have you    小题8:  (曾经) noticed that there are a lot of signs around you and then you receive messages from    小题9: (它们) all the time. It’s necessary to    小题10:  (记住) some of the signs.