原癌基因广泛存在于生物界，在进化过程中高度保守，这类基因属于_爱下问搜题

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问题单项选择题

原癌基因广泛存在于生物界，在进化过程中高度保守，这类基因属于（）

A.细胞癌基因

B.病毒癌基因

C.管家基因

D.抑癌基因

E.调节基因

答案

参考答案：C

阅读理解

阅读下面短文，请从方框中选出适当的句子填入文中的适当位置，使短文内容完整正确。

       Almost everyone likes apple pies in the USA. An apple pie is easy to make.  1   You just need
apples, flour, sugar, butter and spices.
         2   Then mix them with spices and put them in a pie tin.  3   Add the mixture to the apple pieces
and bake the pie for about 45 minutes.   4
       There are many different ways to make apple pies. Some families have their own secret ways and
don't tell other people about them.
         5   but the apple pie perhaps is the dessert that everyone loves best.

Next put butter, sugar and flour together.
So many people make it at home.
First peel and cut the apples into pieces.
Pies made with berries-are also very popular in America.
The smell of the apple pie is great.

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