【单选题】到目前为止,你认为对你英语学习影响最大的是:( )
【简答题】硫与热强碱溶液可生成S 2- 和SO 3 2- ;生成物继续与硫作用得S 2 2- 和S 2 O 3 2- 。过滤后除去过量硫,向滤液中加入一定量的强碱后,再适入足量的SO 2 ,SO 2 与S 2 2- 也完全转化为S 2 O 3 2- 。问: S+SO 2 +OH - 完全转化为S 2 O 3 2- 的离子方程式____________________ amol S最终转化为Na 2 S 2 ...
【单选题】—Help yourself! — _______. [ ]
【单选题】This is a _____ map and it didn’t take me much time to come here from the station. [ ]
【简答题】If they (be) ______ here, they would help you to solve the problems of the computer.
【简答题】碱A(C 8 H 15 ON)是一种生物碱,存在于植物中。不溶于NaOH水溶液而可溶于盐酸中。不与苯磺酰氯作用,但能与苯肼作用生成相应的苯腙。它与NaOI作用生成黄色沉淀和一个羧酸B(C 7 H 13 O 2 N)。用Cr 2 O 3 强烈氧化,B可转化为酸(C 6 H 11 O 2 N),即N-甲基-2-吡咯烷甲酸。试写出A,B的结构式。
【单选题】It is (necessary) that she (comes) here twice a week (to help) (do) the housework.
【单选题】— Betty, will you please come here and help me? — Sorry, she is not here. She _____ to the cinema. May I help you? [ ]