外在水分一般波动较大，直接影响装炉煤的挥发分性能。
参考答案：错
The number of people invited _____ fifty, but a number of them _____ absent for different reasons. [ ]
A. were; was
B. was; was
C. was; were
D. were; were
下表为一项关于儿童健康和发展的研究中10名学龄儿童的身高Y（英尺）和体重X（磅）资料。该资料宜绘制（）
A.直条图
B.百分比条图
C.线图
D.直方图
E.散点图
