护顶作业时从两翼向拱顶进行,喷顶厚度一次可达()。
A.30~50mm
B.50~100mm
C.100~200mm
参考答案:A
.
The little girl _______ reading her favourite book alone under the tree, while the rest _________ talking excitedly about their trip.
A.was, was
B.was, were
C.were, was
D.were, were
结合实际,分析我国行政管理机构绩效不高的原因。