题干

某种鱼的鳞片有4种表现型:单列鳞、野生型鳞、无鳞和散鳞,由两对同源染色体上的两对等位基因(分别用Aa、Bb表示)决定,且BB对生物个体有致死作用。将无鳞鱼和纯合野生型鳞的鱼杂交,F1有两种表现型,野生型鳞的鱼占50%,单列鳞鱼占50%;选取其中的单列鳞鱼互交,其后代有上述4种表现型且比例为6:3:2:1,则F1的亲本基因型组合是()

A:aaBb×AAbb或aaBB×AA

B:AABb×aa

C:aaBb×AA

D:AaBB×Aa

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C

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                                                                                          How Not to Do It All

    We all want to do so much: complete our never ending list of tasks and projects, help everyone, travel everywhere, learn a lot of new skills, read every book and watch every good film. ____ There isn't enough time in the day, nor do we have much attention to devote to everything.

    Give up on trying to do it all. ____ It is important for you to make your days count(有价值). How do you do that? Here are some ideas:

    ____ When you eat a good meal, it's wasted if you actually ignore(不理会)it and are reading on your phone instead. It's an amazing meal only if you really enjoy it. In this way, if we enjoy each moment, they really matter.

    Be satisfied. We always want to do more, be more, experience more. And so, we're never satisfied with the little we actually can do and experience. Instead, we should learn to be happy with what we've chosen to do, knowing that we let go of the rest for a reason. ____

    Realize that we're not really in control. The first few items on this list might give you the idea that you can control your life by simplifying…but the reality is that your day will never go as planned. You can try, but there will always be the unexpected, the unplanned. ____ We should learn to appreciate that experience as it comes, whatever it is.

A. Pay attention.

B. That's just how things go.

C. Yet we can't possibly do them all.

D. Put only the best things in each day.

E. Don't try to have the most perfect life you can create.

F. We can accept the reality that is exposed when we let go.

G. We should be thankful for what's actually in front of us and the experience we are given.