[单选题]Do you know how long our earth _____A. came into existence B. came in existence C. was in existence D. has been in existence
[单选题]下列属于高分子化合物且在自然界中原来并不存在的是[ ]A.淀粉 B.纤维素C.聚乙烯 D.蛋白质
[单选题]Listen to the two girls!What language________?[ ]A.did they speakB.were they speakingC.are they speakingD.have they been speaking
[单选题]— Guess what! Weve got our visas for a short-term visit to the UK this summer. — How nice! You?_____ a different culture then.A. will be experiencingB. have experiencedC. have been experiencing D. will have experienced
[多选题]生活是化学的源泉,下列有关生活中的化学叙述不正确的是A.铁强化酱油可通过膳食补充人体所需的铁元素B.变质的植物油有难闻的特殊气味,是由于植物油发生了水解反应C.一定浓度的双氧水可用于伤口的消毒D.蔬菜中含有维生素C,生吃新鲜蔬菜要比熟吃时维生素C的损失大
[单选题]— Have you seen the movie The Kings Speech — No. Who _____ it?[ ]A. had directed B. has directedC. directedD. directs
[单选题]— Liu Fang, I didnt know you can play the Pipa and Guzheng so well.— Well, actually I ________ it since I was six years old.[ ]A. plays B. have been playingC. playedD. had been playing
[单选题]下列仪中,在实验室进行分液操作时不需选用的是[ ]A.烧杯 B.分液漏斗C.铁架台 D.温度计
[单选题]Our town________poor in the past,but great changes________in the town in the past three years.[ ]A.was;had taken place B.was;have taken placeC.has been;had taken placeD.has been;have taken place
[单选题]某玻璃中含Na2O、CaO、SiO2的质量比约为10∶9∶58,则此玻璃的组成为 [ ]A.Na2O·CaO·6H2SiO3B.Na2O·CaO·6SiO2C.2Na2O·2CaO·9SiO2D.6Na2O·6CaO·SiO2
[多选题]在大气层中,因CO2的含量不断增加而引起“温室 效应”,造成大气中CO2含量增加的主要原因是? [ ]A.由于动植物呼吸作用增加 B.由于实验室逸出的CO2增加 C.由于森林绿化面积迅速递减,使得自然界吸收CO2的能力降低 D.由于大量燃烧矿物燃料
[单选题]He is the only one of the students who _____?a winner of scholarship for three years.A. is B. are C. have been D. has been
[单选题]人生病时要合理用药.下列药品与其作用匹配的是( )A.氢氧化铝:中和过多胃酸B.阿司匹林:消炎抗菌C.青霉素:解热镇痛D.医用碘酒:人体补碘
[单选题]下列说法不正确的是( )A.糖类、蛋白质、醋酸属于天然高分子化合物B.油脂有油和脂肪之分,但都属于酯C.干馏煤可以得到甲烷、苯和氨等重要化工原料D.用大米酿的酒在一定条件下密封保存,时间越长越香醇
[单选题]铝在人体内积累可使人慢性中毒,引起老年痴呆症,世界卫生组织已正式将铝确定为“食品污染源之一”而加以控制,铝在下列使用场合一般无需控制的是[ ]A.铝箔电容 B.牙膏皮 C.制造炊具和餐具 D.糖果香烟包装
[单选题]Now that she is out of work, Lucy going back to school, but she hasnt decided yet. [ ]A. had consideredB. considered C. has been consideringD. is going to consider
[单选题]化学与生产、生活、社会密切相关.下列有关说法中,错误的是A.服用铬含量超标的药用胶囊,会对人体健康造成危害B.血液透析是利用了胶体的性质C.在食品袋中放入盛有硅胶和铁粉的透气小袋,可防止食物受潮、氧化变质D.厨房中燃气泄漏,立即打开抽油烟机排气
[单选题]高一时我们学过醇和酸能生成酯类,“酯”和“脂”音相近、字相似,它们之间既有联系又有区别.天然油脂水解后的共同产物是 [ ]A.硬脂肪酸B.油酸 C.软脂酸D.甘油
[单选题]对于下列常见化学的认识错误的是A.碳酸钙是文物陶瓷的主要成分B.干冰能用于人工降雨C.明矾可用作净水剂D.小苏打是一种膨松剂,可用于制作馒头和面包
[单选题]坏血病患者应该多吃的食物是( )A.鱼肉和猪肉B.水果和蔬菜C.鸡蛋和鸭蛋D.糙米和肝脏
[单选题]近年来,有科学家提出硅是“21世纪的能源”“末来的石油”的观点.假如硅作为一种普遍使用的新型能源被开发利用,关于其有利因素的下列说法中你认为不妥当的是 [ ]A.硅便于运输、贮存,从安全角度考虑,硅是最佳的燃料 B.硅的来源丰富,易于开采,且可再生 C.硅燃烧放出的热量大,且燃烧产物对环境污染较低,容易有效控制 D.寻找高效催化剂,使二氧化硅分解产生硅的同时释放能量,是硅能源大规模开发利用的一项关键技术