灰土地基采用压路机(机重6~10t)压实时,每层最大虚铺厚度可为()mm。
A.100~200
B.200~300
C.300~400
D.400~500
参考答案:B
He was walking along the river __________ he saw a little boy lying under a tree.[ ]
A. while
B. when
C. as
D. which
若想添加页眉和页脚,应使用______菜单中的页眉和页脚命令。