雷达变送器向液体表面发射微波,然后接收从表面反射的回波,()正比于被测距离.A.发射 发布时间:2017-07-11 02:38 │ 来源:www.tikuol.com 题型:单项选择题 问题: 雷达变送器向液体表面发射微波,然后接收从表面反射的回波,()正比于被测距离.A.发射波与反射波间的波长差B.发射波波长C.反射波波长D.发射波与反射波间的时差
题型:单项选择题 某宇航员站在一颗星球表面上的某高处,沿水平方向抛出一个小球,经过时间t ,小球落到星球表面,测得抛出点与落地点之间的距离为L.若抛出时的初速度增大2倍,则抛出点与落地点之间的距离变为L.已知两落地 点在同一水平面上,该星球的半径为R,万有引力常量为G,求该星球的质量M. 查看答案
题型:单项选择题 (5分)根据要求写出下列方程式,并注明基本反应类型。⑴用稀盐酸除铁锈_________( )反应⑵氢氧化铜加热生成两种氧化物__ ______( )反应⑶甲烷燃烧______________________ 查看答案
题型:单项选择题 在天气晴朗的早晨,摘取一植物的叶片甲,于100℃下烘干,称其质量,到黄昏时,再取同一植株的相同位置、相同形态大小的叶片乙,同样处理,称其质量,其结果为[ ]A.甲叶片比乙叶片质量小 B.甲叶片比乙叶片质量大 C.两叶片质量一样 D.不一定 查看答案
题型:单项选择题 阅读理解。 LET YOUR LOVE FOR ANIMALS LIVE ON As someone who loves animals, you care about what willhappen to them in the future. CSIA has been treating sick andinjured animals since 1939. It's hard to imagine what would happen to the hundreds of thousands of pets who need us every year if we no longer existed. But in fact, we simply could not continue if it wasn't fora very special kind of gift people like you leave to us in their wills (遗嘱). Can we depend on your kindness too? If you haven'talready done so, please consider including a gift to CSIA inyour will. For free information on how to go about it, pleasecall our helpline on 0800 8421950. Your love for animals canlive on with a gift in your will to CSIA. CSIA for pets in need of vets (兽医) 1. This advertisement is trying to persuade people to _____. A. buy a gift for a pet B. give money for animal careC. work for an animal hospital D. treat sick and injured animals 2. The advertisement is mainly aimed at _____. A. vets B. zoo-keepersC. old pet lovers D. animal hospital assistants3. What is CSIA most likely to be? A. A pet shop B. An animal hospital C. A club for pet lovers. D. A training center for vets. 查看答案