阅读理解。 If you go into the forest (森林) with friends, stay with them. If you don't, you may get lost (丢失). 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 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 (吹口哨) three times. Stop. Then shout or whistle three times again. Any signal (信号) given three times is a call for help. Keep up shouting or whistling. Always three times together. When people hear you, they will give you two shouts or two whistles. When a signal is given twice, it is an answer to 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). Make yourself a bed with leaves (树叶) and grass. When you need some water, you have to leave your little branch house to look for it. Don't just walk away. Pick off small branches and drop (扔) them as you walk in order to go back again easily. When you are lost, the most important thing to do is stay in one place. 1. If you get lost in the forest, you should _______. [     ] A. try to find your friends B. stay in one place and give a signals C. walk around the forest D. shout as loudly as possible 2. Which signal is a call for help? [     ] A. Shouting here and there B. Crying twice C. Shouting or whistling three times together D. Whistling everywhere in the forest 3. When you hear two shouts or two whistles, you will know that _______. [     ] A. someone is afraid of an animal B. people will come to help you C. someone needs help D. something terrible will happen 4. What do you have to do when you leave for water? [     ] A. Leave branches as you walk to find way later B. Pick off branches to build another house C. Use branches to make a bed D. Drop branches to look for water 5. The main idea of the passage is ________. [     ] A. how to travel in the forest B. how to spend the night in the forest C. what you should do if you want to get some water D. what you should do if you are lost in the forest