最大粒径31.5㎜碎石或卵石的筛分析试验所需试样的最少数量为()kg。
A、20
B、15
C、63
D、25
参考答案:D
We must take two aspects into consideration, both of __________ associated with the safety of the students .
A.which
B.whom
C.that
D.them
This kind of fish is not( )for human consumption.
A.fit B.be fit C.well D.fine