Mark was a student at this university from 1999 to 2003, _____ he studied very hard and wa

Mark was a student at this university from 1999 to 2003, _____ he studied very hard and was made Chairman of the Students’ Union.

A during which time B for which time C during whose timeD by that time

答案

若以ω1和ω2分别表示浓度为amol•L﹣1和bmol•L﹣1氨水的质量分数，且知2a=b，则下列推断正确的是（氨水的密度比纯水的小）（）A．2ω1=ω2B．2ω2=ω1C．ω2

(2019.呼和浩特)某固体可能含有CaCl2、Na2SO4、CuSO4、KNO3、Na2CO3中的一种或几种，现对其进行如下实验: ①取少量固体于试管中，加适量蒸馏水，固体完全溶

《汉书·艺文志》在评价战国时期的某一学派时说：“盖出于史官，历记成败存亡祸福古今之道，然后知秉要执本，清虚以自守卑弱以自持，此君人南

在CuSO4和AgNO3的混合溶液中加入一定量的铁粉，充分反应后过滤，得蓝色滤液和沉淀，下列判断正确的是 A．滤液中一定有、、 B．沉淀中可能有Cu C．

某一质点做简谐运动的位移x与时间t的关系图如图2所示，由图2可知，在t=1s时，质点的速度和加速度为： A．速度为零，加速度为正的最大值 B．速度为

有①镊子、②烧杯、③试管、④胶头滴管、⑤药匙、⑥100 mL量筒、⑦10 mL量筒、⑧托盘天平等仪器。请为下列实验操作各选一种仪器(填写相应的序号)：

有些同学知道上课时间手机上网对学习影响很大，但总是不由自主。你的做法是①以坚强意志抵制不良诱惑②坚决不带手机到课堂，避开诱因③培养学

—You've made great progress in your studies of English, haven't you? —Yes, but much________to be done. A. leaves B.keeps C. remains �