采用统计方法评定混凝土强度时,当混凝土强度等级不高于C20时,其强度的最小值尚应满足()要求。
A.≤0.90
B.≤0.85
C.≥0.85
D.≥0.90
参考答案:C
Susan and Lily______tomatoes a nd other vegetables on the farm this time yesterday.
A.pick
B.are picking
C.will pick
D.were picking
怎样合理地选用金属材料.