题目

下图所示装置可用于测定空气中氧气的含量，实验前在集气瓶内加入少量水，并做上记号。下列有关该实验的说法中，正确的是A. 红磷燃烧的化学方程式为P + O2 P2O5B. 红磷熄灭后，立刻打开弹簧夹C. 最终瓶中剩余的气体是纯净的氮气D. 瓶中液面最终上升至1处，证明空气中O2含量约为1/5体积 答案：【答案】D【解析】A、该反应的化学方程式没有配平，红磷燃烧的化学方程式为4P+5O22P2O5，故A错误。B、红磷熄灭后，不能立刻打开弹簧夹，因为此时剩余的气体在受热状态下，处于膨胀状态，占据了部分水的体积，立刻打开弹簧夹读数偏小，故B错误。C、最终瓶中剩余的气体是氮气、稀有气体、二氧化Volunteers are neededClean People’ s Park!We need five people who are strong and can help clean up people's park. We need help to collect rubbish If you are free for four hours this weekend, come and join us!Tel:0398-8651518Email:park699@126.comTeach Music!We need three volunteers to work as music teachers in SOS Children’s Villages. You needto be good at singing and dancing, and open-minded with a loving heart.If you are free for two hours every weekend, join us!Tel:0398-8858518Email: lovekids(@sina.comHelp old people!We need four volunteers to help at Xinxin nursing home, You need to be good with older people. Your job is to wash clothes for them.If you can spare three hours on May 6, come and join us!Tel:0398-8656869Email:homelove@163.com1.If you are free for_____ this weekend, you can help clean people's ParkA. two hours B. three hours C. four hours D. five hours2.The SOS children's Villages need three volunteers to teach kids_______.A. maths B. music C. science D. physics3.To volunteer in SOS children's Villages, you need to________.A. be strong and helpful B. be interested in natureC. be creative and love kids D. be good with kids4.Volunteers are asked to _________at Xinxin Nursing home.A. collect rubbish B. teach EnglishC. learn music D. wash clothes5.________volunteers are needed in all according to the poster.A. Three B. Four C. Five D. Twelve6.Of the following information, ___________is NOT true.A. If you can help collect rubbish, you can call 0398-86515iB. Music teachers need to work for two hours every weekendC. You can send an email to homelove(@163.com to help kidsD. Xinxin nursing home needs volunteers to wash clothes on May 6. 1.C 2.B 3.C 4.D 5.D 6.C 【解析】本文介绍了打扫公园，SOS儿童村和鑫鑫养老院需要志愿者，以及这些志愿者应做的事。 1.C 细节理解题。根据If you are free for four hours this weekend, come and join us!可知如果你周末有四个小时的空闲时间，你可以来帮助打扫人民公园，故选...