①A，B用导线相连后，同时浸入稀硫酸溶液中，A极为负极；

②C，D用导线相连后，同时浸入稀硫酸溶液中，电流由D→导线→C；

③A，C相连后，同时浸入稀硫酸溶液中，C极产生大量气泡；

④B，D相连后，同时浸入稀硫酸溶液中，D极发生氧化反应．

据此，判断四种金属的活动性顺序是（   ）

根据汉语意思完成英语句子，每空一词。

根据短文理解，从A、B、C、D四个选项中选择最佳答案填空。

    Tolstoy, the great Russian writer, liked to walk about in a railway station near his home. One day when he was walking up and down as usual, looking at people getting on and off the 1, he heard a lady 2 after him, “Hey, you old fellow, go and fetch my handbag in the 3  room which I left there.”

    Tolstoy 4 there. He 5 the bag up and walked quickly along the platform (站台）. At the same time the lady was waiting beside the carriage, looking  6. When at last the old man gave the bag back to her, she opened it to 7 sure nothing was missing. “Good, old man,” said the woman. “You are just as 8 as I hope. Here you are.” Tolstoy 9 the coin and put it into his pocket with a smile.

    But the woman was very 10 when she heard that he was Tolstoy, the author (作者）of the great novel WAR AND PEACE. How interesting it was!