产生克隆羊多利的卵细胞的细胞核来自于（　　）

某同学用如图所示的装置做验证动量守恒定律实验．先让a球从斜槽轨道上某固定点由静止开始滚下，在水平地面上的记录纸上留下压痕，重复10次；再把同样大小的b球放在斜槽轨道末端水平段的最右端附近静止，让a球仍从原固定点由静止开始滚下，和b球相碰后两球分别落在记录纸的不同位置处，重复10次．

增加：在缺词处加一个漏词符号(/\)，并在其下面写出该加的词。

删除：把多余的词用斜线(\) 划掉。

修改：在错的词下画横线，并在该词下面写出修改后的词。

注意：1）每处错误及其修改均仅限一词;

2）只允许修改10处，多者(从第11处起)不计分。

    On Sunday, Miss Green told Lisa, Jack and Lily a story about a girl names Cathy, who is just 12 years old. One day, when she was at the home, her mother careless cut her finger, which immediately started bleeding. As a little girl, Cathy didn't get a panic. Instead, she calmly cleaned her mother wound and then stopped it from bleed. She did that so she had just learned how to give first aid. Then Miss Green encouraged both of them to learn more about first aid. “It's really important because it can not only helps deal with injuries but also save life,” she said. After hearing it, they decide to learn first aid skills.

如图所示是航母舰载飞机训练时的图片．下列说法中正确的是

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