问题 选择题

硼化钒(VB2)-空气电池是目前储电能力最高的电池,电池示意图如下,该电池工作时反应为:4VB2 + 11O2→ 4B2O3 + 2V2O5 。下列说法正确的是

A.电极a为电池负极

B.图中选择性透过膜只能让阳离子选择性透过

C.电子由VB2极经KOH溶液流向a电极

D.VB2极发生的电极反应为:2VB2 + 22OH- 22e→V2O5 + 2B2O3 + 11H2O

答案

答案:D

题目分析:根据电池反应式确定该电池的负极为VB2-e→V2O5 + 2B2O3,正极为氧气得到电子。A、a通入氧气,故该极为正极,错误;B、该电池正极产生氢氧根离子,负极消耗氢氧根离子,所以透过膜应是让阴离子透过,错误;C、溶液不能有电子通过,错误;D、正确。

完形填空
My sister, Cathy, who lives in Vancouver, sent me a package full of Christmas gifts. She told me that she had 36   it in advance to make sure it would arrive at my house weeks before the 37 . Christmas was drawing near, but no package arrived. Cathy checked the tracking number every 38  with Canada Post, and every evening she would call me to 39  if there was any sign of it on our end.
The 40  always started with questions about the package, but twenty minutes later we would still be 41   . We talked about our family, such as parents, our kids, 42  and so on. Of course we also talked about our jobs. We had never made so much 43  for each other! The talk always took us back to the hours we spend together in our childhood.
By Christmas Eve we finally had to 44   the fact that the package was 45  lost. On Christmas morning, Cathy got on the phone with everyone in my 46   and told them what she had sent. Later on, after a big Christmas dinner, I had forgotten all about the 47  package when there was a knock on the door. Who could it be at such a time? As I 48  the door, a man was standing there. “I 49    this is yours.” he said, holding a package. Just then I 50  that it had been delivered to the wrong address. “I just got home from vacation,” he explained, “51 I wanted you to have this in time to open for Christmas.” I thanked this 52  stranger for taking so much trouble to 53 this gift to us on Christmas Day, and 54 thanked God that the package had been lost in the first place.
The real gift that holiday season was the new 55  to my sister who lives far away from us. Now there’s one gift I never want to give back!
小题1:
A.booked B.decoratedC. listedD.mailed
小题2:
A.appointmentB.deadlineC.holidayD.party
小题3:
A.yearB.morningC.weekD.month
小题4:
A.pick outB.take outC.figure outD.find out
小题5:
A.complaintB.conversationC. discussionD.quarrel
小题6:
A.chattingB.arguingC. kiddingD.scolding
小题7:
A.gifts B.secretsC.husbandD.clothing
小题8:
A.foodB.timeC.achievementD.money
小题9:
A.considerB.ignoreC. acceptD.study
小题10:
A.entirelyB.simplyC.mostlyD.suddenly
小题11:
A.restaurantB.officeC.houseD.class
小题12:
A.terribleB.outstandingC.bigD.missing
小题13:
A.openedB.lockedC.leftD.watched
小题14:
A.understandB.forgetC.knowD.believe
小题15:
A.expectedB.dreamedC.realizedD.remembered
小题16:
A.becauseB.butC.orD.so
小题17:
A.generousB.honestC.politeD.kind
小题18:
A.showB.presentC.returnD.offer
小题19:
A.silentlyB.carefullyC.gentlyD.actually
小题20:
A.connectionB.guideC.recognitionD.closeness
单项选择题