I'm going ____________ the stairs. [ ]
A. to
B. in
C. too
答案：A
—Where is your homework?
—I'm sorry. I forgot _______ my homework. [ ]
A. to bring
B. bringing
C. to take
D. taking
对计数资料进行描述的主要指标是( )
A．均数B．相对数C．标准差D．中位数E．四分位数间距
