扣件式钢管脚手架作业层脚手板应铺满、铺稳,离开施工封面不宜大于()mm
A、80-100
B、100-120
C、120-150
D、150-180
参考答案:C
The students entered the classroom, smiling and ______, and ______ down to have their lessons.[ ]
A. talked; sat
B. talking; sitting
C. talking; sat
D. talked; sitting
Wilcoxon符号秩检验是检验()。