由某一基因表达后，对另一基因转录进行调控的是（）
A．顺式作用因子
B．反式作用因子
C．反式作用DNA
D．顺式作用元件
E．反式作用元件
参考答案：B
— Sorry, I can't work out this problem.
— Try again, please. It's only difficult. [ ]
A. a bit
B. a lot
C. very
D. much
单项选择。
We don't have ______ meat. I want to buy some.[ ]
A.many
B.much
C.a lot
D.some
