直方图的每个条形的宽度表示各组频数或频率，高度表示组距宽度。（ ）
参考答案：错
脓疱型银屑病可出现：
A．水痘B．传染性软疣C．扁平疣D．天疱疮E．带状疱疹
-----An ant has two stomachs --- one for itself, one for others.
-----Really? Quite interesting. I ____ anything about it.
A．don’t know
B．have known
C．haven’t known
D．didn’t know
