用同一支密度计，当浸入密度较大的液体中时，密度计浸没较多；浸入密度较小的液体中时，密度计浸没较少。
参考答案：错
色氨酸操纵子比乳糖操纵子多了（）系统。
The rock band is going on a world tour in ______they will perform in different cities.
A．that
B．which
C．whom
D．where
