高粘度液体搅拌时，效果最好的是（）式搅拌器。
A.框
B.螺带
C.螺杆
D.螺带、螺杆
参考答案：D
All of them felt it necessary that they______ __the meeting.
A．attend
B． would have attended
C．attended
D． were to attend
影响排烟损失的主要因素是排烟（）和排烟量。
