题干

在1~18号元素中,最外层上的电子数与电子层数相同,该元素可能有(   )

A:1种

B:2种

C:3种

D:4种

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答案(点此获取答案解析)

C

同类题1

阅读理解

    A little boy invited his mother to attend his school's first teacher-parent meeting. To the little boy's dismay(沮丧), his mother said she would go. This would be the first time that his classmates and teachers met his mother and he was embarrassed by her appearance. There was a severe(严重的) scar (伤疤) that covered nearly the whole right side of her face. The boy never wanted to talk about why or how she got the scar.

    At the meeting, the people were impressed by the kindness of his mother with the scar, but the little boy was still embarrassed and hid himself from everyone. However, he could hear clearly the conversation between his mother and the teacher.

     “How did you get the scar on your face?” the teacher asked.

    The mother replied, “When my son was a baby, he was in a room that caught on fire. Everyone was too afraid to go in because the fire was out of control, but I went in. As I was running towards his bed, I saw a burning wood falling down and I placed myself over him trying to protect him. I was knocked to be unconscious(无知觉的), but luckily, a fireman came in and saved both of us.” She touched the burned side of her face. “This scar will be forever, but until today, I have never regretted doing what I did.”

    When the little boy heard this, he couldn't help running towards his mother with tears in his eyes. He hugged her and felt his mother was greater than anyone. He held her hand tightly for the rest of the day.

同类题3

阅读短文,并将空格补充完整,使短文通顺,意思完整。(每空一词)

    A Little Horse Crossing the River

    There is an old horse and a little horse on a farm. One day the old horse asks the little horse to send the wheat to the mill(磨坊)。The little horse is very happy. He carries the wheat and runs toward the mill. But there is a river in front of the little horse. He stops and doesn't know ____ to do next. Just then Aunt Cow is passing by.

    The little horse ____,”Aunt Cow, please tell me. Can I cross the river?”

Aunt Cow answers.” It's not deep, you can cross it.”

    When the little horse begins to cross the river, a little squirrel(松鼠)shouts to him,” Little horse, don't cross it, you will be drowned. Yesterday ____ of my friends was drowned in this river.”

    The little horse is very ____ .Finally he ____ to go home and asks his mother.

    The old horse asks,”____ do you take the wheat back? What's wrong with you, my child?”

    The little horse answers sadly,” There is a river in front of me. Aunt Cow said it was not deep, but the little squirrel said it was deep. What shall I do?”

    The old horse says,” My child, you should try to cross the river by   7    . If you don't try, how do you know the river is deep or not.

    The little horse carries the wheat and    8      to the riverside. At last,he succeeds in   9    the river. Now, he knows    10    deep the river is.