阅读理解。 If you go into the forest with friends, stay with them. If you get lost, this is what you should do. Sit down and stay where you are. Don't try to find your friends, let them find you. You can help them to find you by staying in one place. There is another way to help your friends or other people to find you. You can shout or whistle three times. Stop. Then shout or whistle three times again.  Any signal given three times is a call for help. Keep up the shouting or whistling always three times together. When people hear you, they will know that you are not just making noise for fun. They will let you know that they have heard your signal. They will give you two shouts or two whistle. When a signal is given twice, it is an answer to a call for help. If you don't think that you will get help before night comes, try to make a little house with branches (树枝) and lots of leaves. Make yourself a bed with leaves and grass. When you need some water, you have to leave your little branch house to look for a stream. Don't just walk away. Pick off small branches and drop them as you walk in order to find the way back. 1. If you get lost in the forest, you should _____ . A. just get lost in the forest B. walk round the forest and shout C. stay in one place to give signals D. build a house 2. How to let people believe that you aren't just making noise for fun? A. Shout that you're lost. B. Whistle all the time. C. Keep silent. D. Give the shouting or whistling always three times together. 3. When you hear two shouts or two whistling, you know that _____. A. a beast will come B. the birds are singing C. something terrible will happen D. people will come to help you 4. The article tells you _____ . A. what you should do if you are lost in the forest B. how to spend the night in the forest C. how to travel in the forest D. how to build a branch house 5. Which is the best title for the passage? A. What to Do When You Get Lost. B. Stay With Your Friends. C. Make Signal in the Forest. D. How to Get Out of the Forest.