粗骨料表观密度试验，当两次结果之差大于（）kg／m3时，应重新取样进行试验。
A、10
B、20
C、30
D、40
参考答案：B
The professor you referred to in the letter______ us students three lectures by next Monday.
A．has given
B．will given
C．will have given
D．Gave
降香饮片的干燥温度适合在（）
A.80℃
B.75℃
C.70℃
D.60℃
E.50℃
