[单选题]— Can I have a talk with you at about 4 this afternoon,Mr Black— All right, I ________ from a conference by then. I will be waiting for you.A. will have come backB. will come backC. have come backD. will be coming back
[单选题]下列说法不正确的是( )①化石燃料在任何条件下都能充分燃烧②化石燃 料在燃烧过程中能产生污染环境的CO、SO2等有害气体③直接燃烧煤不如将煤进行深加工后再燃烧 的效果好④固体煤变为气体燃料后,燃烧效率将 更低 A.①④ B.②③④C.②③ D.①③④
[单选题]下列常用的实验仪器中,不能直接用于混合物分离或提纯的是( )A.分液漏斗B.普通漏斗C.蒸馏烧瓶D.容量瓶
[单选题]已知甲酸HCOOH可以写成CO(H2O),在50--60℃时,向甲酸中加入浓硫酸会发生脱水生成CO.则草酸HOOC-COOH与浓硫酸在一定温度下脱水会生成[ ]A、CO B、CO2C、CO和 CO2D、C2O3
[单选题]Because the shop _______, the T-shirts are sold at half price. [ ]A. has closed downB. closed downC. is closing downD. had closed down
[单选题]合理使用药物有利于身心健康.下列有关说法正确的是( )A.氯化钠用于治疗胃酸过多B.阿司匹林常用于解热镇痛C.青霉素是一种常用的抗生素D.非处方药都无毒副作用、可长期大量服用
[单选题]It was raining hard, but by the time the class was over, the rain _______.[ ]A. had stoppedB. was stoppingC. stopped D. would stop
[单选题]化学与环境保护、工业生产、生活等密切相关.下列说法不正确的是A.加速建设地铁、轻轨等轨道交通,促进城市一体化发展,减少汽车尾气排放B.大力实施矿物燃料“脱硫、脱硝技术”,减少硫的氧化物和氮的氧化物污染C.发展低碳经济、循环经济,推广可利用太阳能、风能的城市照明系统D.晶体硅具有半导体性质,可用于生产光导纤维
[单选题]Robert _______ a book about his experiences in China.I hope he can find a good publisher when it is finished. [ ]A. was writingB. is writingC. has already writtenD. wrote
[单选题]I hadn’t seen him for years but I _____ him at first sight.A.realizedB.spottedC.combinedD.observed
[单选题]—What do you think of my suggestion—What suggestion? I about something else.[ ]A. was thinkingB. am thinkingC. thoughtD. think
[单选题]起固定氮作用的化学反应是[ ]A.N2和H2在一定条件下反应生成NH3B.NO与O2反应生成NO2C.NH3催化氧化生成NOD.由NH3制NH4HCO3和(NH4)2SO4
[单选题]— He _____ without our help. — Yes, I know. We have to admit that nobody can match him. [ ]A. would not have succeeded B. has succeeded C. should have succeededD. has failed
[单选题]甲醛与亚硫酸氢钠的反应方程式为HCHO+NaHSO3HO-CH2-SO3Na,反应产物俗称“吊白块”.关于“吊白块”的叙述正确的是 [ ]A.易溶于水,可用于食品加工 B.易溶于水,工业上用作防腐剂 C.难溶于水,不能用于食品加工 D.难溶于水,可以用作防腐剂
[多选题]下列有关高分子化合物性质描述中不正确的是[ ]A.一般具有良好的绝缘性 B.均不溶于水,易溶于有机溶剂C.均不耐热,受热后会熔化,改变原有形状 D.一般比同质量的金属强度大
[单选题]在医院中,为酸中毒病人输液不应采用 [ ]A.0.9%氯化钠溶液 B.0.9%氯化铵溶液 C.1.25%碳酸氢钠溶液 D.5%葡萄糖溶液
[单选题]对于某些合成材料和塑料制品废弃物的处理方法正确的是[ ]A.将废弃物混在垃圾中填埋在土壤中 B.将废弃物进行焚烧处理 C.将废弃物加工成涂料或汽油 D.将废弃物倾倒在海洋中
[单选题]1,4-二氧六环是一种常见溶剂,它可以通过下列合成路线制得,则烃A应是CH2-CH2怪类2目x浓H。S0水溶液H20CH2-CH2A.1-丁烯B.1,3-丁二烯C.乙炔D.乙烯
[单选题]下列说法中,不正确的是 []A.用于溶解涂料中的成膜物质的有机溶剂会污染环境 B.黏合剂的主要成分是各种树脂,如酚醛树脂、脲醛树脂等C.合成高分子材料包括塑料、合成纤维、合成橡胶、涂料、黏 合剂、高分子分离膜等 D.“白色污染”指的是废弃的塑料制品对环境造成的污染
[单选题]Unrest and violence in North A.rica and the Middle East ____ at their fastest rate since 2008. ?[ ]A. have been raisingB. have been rising C. have raised D. have risen
[单选题]蛋白质的下列哪个性质可以用于蛋白质的提纯分离( )A.水解B.盐析C.变性D.颜色反应