题目

(本小题满分14分) 在如图所示的多面体中,已知正三棱柱的所有棱长均为2,四边形是菱形. (Ⅰ)求证：平面平面. (Ⅱ)求该多面体的体积. 答案：（Ⅰ）证:由正三棱柱,得,而四边形是菱形,所以, 又平面且,所以平面…………………………5分 则由平面,得平面平面…………………………………………… 7分 (Ⅱ)因为正三棱柱的体积为………………………………10分 四棱锥的体积为……………………………………13分 所以该多面体的体积为…………… One of the hottest places on the earth is Death Valley. It's a desert valley in North America. The animals in Death Valley don't use technology to keep cool. They have special abilities that help them live there. The kangaroo rat is one of the animals that live in Death Valley. During the day in Death Valley, it gets hotter than 100°F. The kangaroo rat rests all day in a hole in the ground. It covers the hole with grass to keep out the heat. The kangaroo rat comes out at night when it is cooler. This little rat is also very good at conserving(节约) water. It gets all the water it needs from the food it eats. Some kangaroo rats never take a drink of water in their whole lives.The sun makes the desert sand very hot. Animals, like snakes, get too hot if they lie on the hot sand too long. One snake, called the sidewinder, can solve this problem. When it travels, the sidewinder bends its body into a “W” shape. Then it uses the bottom parts of the “W” like legs and walks sideways (向一侧). That way it touches only a little of the sand at a time, so the hot sand doesn't burn the snake. This strange way of moving is how the sidewinder got its name. Most of water in the desert is too salty for most animals to drink. All water has some salt in it. As the desert heat dries up pools of water, the salt is left behind. The remaining water in these pools can be much saltier than those in the ocean. One kind of fish, the desert pupfish, can live in these salty pools because it can drink the salt water.14题完成句子；15、16题简略回答问题；17题用英语简要概括本文的主旨大意；18题将文中画线句子译成汉语。【1】The animals in Death Valley have ____________ that can help them live there.【2】Why does the kangaroo rat cover the hole with grass?________________________________________________________________________【3】What kind of shape does sidewinder bend itself into?________________________________________________________________________【4】The passage mainly tells us about ______________ in Death Valley.【5】________________________________________________________________________