[单选题]The?US?troops_______?out?of?Iraq?by?the?end?of?next?month?and?they?were?sent?there?9?years?ago.A.?have?withdrawnB.?will?withdrawC.?had?withdrawnD.?will?have?withdrawn
[单选题]油脂是油与脂肪的总称,它是多种高级脂肪酸的甘油酯.油脂既是重要食物,又是重要化工原料.油脂以下性质和用途与其含有的不饱和双键(C=C)有关的是( )A.适量摄入油脂,有助于人体吸收多种脂溶性维生素和胡萝卜素B.利用油脂在碱性条件下水解,可以生产甘油和肥皂C.植物油通过氢化,即与氢气发生加成反应可以制造植物奶油(人造奶油)D.脂肪是有机体组织里储存能量的重要物质
[单选题]日常生活中的下列物质,属于合成材料的是( )A.羊毛B.棉线C.尼龙绳D.真丝巾
[单选题]下列说法正确的是A.医疗上可用硫酸钡作X射线透视肠胃的内服药,主要原因是硫酸钡不溶于水B.金属材料都是导体,非金属材料都是绝缘体C.PM2.5是指大气中直径小于或等于2.5μm的颗粒物,我国已将其纳入空气质量检测范围D.钢铁在海水中比在河水中更易腐蚀,主要原因是海水含氧髙于河水
[单选题]下列物质属于硅酸盐材料的是? [ ]A.碳纤维B.石灰石 C.普通水泥D.水晶
[单选题]The International Day against Drugs, aimed at warning people to keep away from drugs, ______ on June 26th every year. ( )A. taking place B. takes place C. took place D. taken place
[单选题]下列物质中,不属于天然高分子化合物的是 ( )A.牛油 B.蚕丝 C.酚醛树脂 D.淀粉
[单选题]下列有关化石燃料的说法正确的是( )A.化石燃料是可再生的,因此地球上的蕴藏量也是无限的B.化石燃料虽然在地球上的蕴藏量有限,但形成化石燃料的速率相当快,所以化石燃料相当于是无限的C.化石燃料的形成非常复杂,需时间较长,但化石燃料在地上的蕴藏量是无限的D.化石燃料在地球上的蕴藏量是有限的,而且又都是非再生能源
[单选题]下列物质一定不是天然高分子的是( )A.橡胶B.羊毛C.聚乙烯D.纤维素
[单选题]— Jim, have you finished reading the novel— No. I _____?my father on the farm all day yesterday.A. would help B. was helping C. had helpedD. have been helping
[单选题]核糖是合成核酸的重要原料,结构简式为:CH2OH-CHOH-CHOH-CHOH-CHO.下列关于核糖的叙述不正确的是 [ ]A.是高分子化合物 B.在一定条件下可以与羧酸发生酯化反应 C.分子式为C5H10O5D.在加热条件下可与新制Cu(OH)2反应
[单选题]Ladies and gentlemen, please fasten your seat belt. The plane ______.( )A. takes offB. is taking offC. has taken off D. took off
[多选题]2009年诺贝尔化学奖授予万卡特拉曼-莱马克里斯南等三人,以表彰他们在核糖体的结构和功能方面研究所作出的贡献.核糖体是进行蛋白质合成的重要细胞器,能制造蛋白质.下列关于蛋白质的说法中正确的是( )A.蛋白质分子中只含有C、H、O、N元素B.只有高温、重金属盐和紫外线才能使蛋白质变性C.误食重金属盐,可立即喝牛奶或生鸡蛋清进行解毒D.向蛋白质溶液中加入饱和的(NH4)2SO4溶液,蛋白质会析出,再加水又会溶解
[单选题]— Watch! — I ____ but ____ I ____ anything unusual. [ ]A. watched; have watched B. have watched; am not seeing C. was watching; wasnt seeing D. am watching; dont see
[单选题]— I havent finished my essay because the computer broke down when I was downloading the required data last night.— Really! You could have turned to me. I mine. [ ]A. didnt useB. wont useC. hadnt usedD. wasnt using
[单选题]A.cording to the timetable, the train for Beijing ____ at four in the afternoon. [ ]A. leavesB. is leaving C. will leave D. leave
[单选题]为了更好的解决能源问题,人们一方面研究如何提高燃料的燃烧效率,另一方面寻找新能源.以下做法不能提高燃料效率的是 [ ]A. 煤的汽化与液化 B. 液体燃料呈雾状喷出 C. 通入大大过量的空气 D. 将煤粉粉碎
[单选题]They said at last that they ____ better start out at once. [ ]A. had had B. had C. had been D. was
[单选题]化学与生产、生活、社会密切相关,下列有关说法中不正确的是A.央视曝光“毒胶囊”事件,主要是其中重金属含量超标,重金属对人体危害主要是使蛋白质变性B.大量焚烧田间秸秆会产生雾霾,“雾”和“霾”的分散质微粒相同C.人体内没有能使纤维素水解成葡萄糖的酶,因此纤维素不能作为人类的营养食物D.针对H7N9流感的扩散情况,常选用含氯消毒剂、双氧水等物质进行消毒预防
[单选题]-I talked to him over the matter last night.-So you there after all.[ ]A. are goingB. do wentC. were going D. did go
[单选题]I _____ ping-pong quite well, but I havent had time to play since the new year. ?[ ]A. will play B. have played C. played D. play