题干

下图是同一种动物体内有关细胞分裂的一组图像,下列说法中正确的是(   )

A:具有同源染色体的细胞只有②和③

B:动物睾丸中不可能同时出现以上细胞

C:③所示的细胞中不可能有基因重组

D:上述细胞中有8条染色单体的是①②③

上一题 下一题 0.0难度 选择题 更新时间:2018-10-23 09:04:07

答案(点此获取答案解析)

C

同类题3

阅读下面短文,掌握其大意,然后从各小题所给的四个选项中选出最佳选项。

    One thorn(刺) of experience is worth many times of warning.

    Ralph Wick was seven years old. In most things he was a fine boy, but he would cry from time to time. When he could not have what he wanted, he would 1for it. If he was told that it would hurt him, and he could not 2 it, he would also cry.

    One day, he went with his mother into the 3. The sun shone. The grass was cut. The flowers were starting to come out.

    Ralph thought he was, for once, a good boy. A 4 was on his face. He wished to do as he was told. Ralph helped his mother with the farm work and he was very happy.

    “Now you must be tired and 5,” said his mother. “Have a good rest here and eat some cookies. I will get a beautiful red rose for you.” So his mother brought the red flower to him. When he saw his mother still had a white rose in her hand, Ralph 6 it.

    “No, my dear.” said his mother. “See how many thorns it has. You must not touch it, or you would be sure to hurt your 7.” When Ralph found that he could not have the white rose, he began to cry, and 8 took it away. But he was soon very sorry. The thorns hurt his hand. It was so 9 that he could not use it for some time.

    Ralph would never 10 this. From then on, when he wanted what he should not have, his mother would point to his hand which had been hurt before. He at last learned to do as he was told.