【单选题】《红楼梦》中,“刘姥姥进大观园”,这在今天变成了一句俗语——大开眼界。按照曹雪芹的构思,刘姥姥进荣国府,一共进了几次?
【单选题】We need to know something about the structure and operation of science because ______.
A.
it is not easy to understand the things that excite and frustrate scientists
B.
Science affects almost every aspect of our life
C.
Scientists live in a specific subculture
D.
It is easier to understand general characteristics of science
【单选题】直流稳压电源电路中,滤波的作用是()。
C.
将整流后的脉动直流中的谐波分量滤掉,使波动变平滑.
【单选题】We need to know something about the structure and operation of science because ______.
A.
it is not easy to understand the things that excite and frustrate science
B.
science affects almost every aspect of our life
C.
scientists live in a specific substructure
D.
it is easier to understand general characteristics of science
【单选题】We need to know something about the structure and operation of science because ______.
A.
it is not easy to understand the things that excite and frustrate the scientist
B.
science affects almost every aspect of our life
C.
scientists live in a specific subculture
D.
it is easier to understand general characteristics of science
【单选题】铅中毒问题中,模型所涉及的变量为( ) .