When I was a child in kindergarten, I had to take a nap(小睡) every single day. It was ____(probable) my least favorite thing about being in kindergarten.

    But now, as ____ adult, I love taking naps. Being able to relax and get some rest in the middle of the day is great! But attitudes toward naps ____ (be) quite different when comparing the US and China.

    In the US, taking a nap in the middle of the day ____ (look) down upon. People ____ take naps are seen as lazy. If you fall ____(sleep) at work, you can even be fired. But in China people have a much more relaxed attitude toward taking naps ____ in the US.

    On the one hand, it is true that you spend less time ____ (work) if you take a nap. But on the other hand, having a short rest can help you work ____(well). A good rest can improve your mood as well. ____why not take a nap during lunch break and make the rest of the day more enjoyable?

双亲正常，生出了一个染色体组成为44+XXY的孩子（未发生基因突变），关于此现象的分析，正确的是（　　）

1958年科学家Taylor用³H标记蚕豆根尖细胞（含12条染色体）的DNA分子双链，再将这些细胞转入不含³H标记的培养基中培养，在第二次细胞分裂的中期和后期，一个细胞中被标记的染色体条数分别是