可摘局部义齿咬合增高的原因不包括（）
A.填塞塑料过多
B.填塞塑料过硬
C.装盒的方法选择不当
D.型盒未压紧
E.型盒内石膏强度不够
参考答案：C
3α+3α=6α______．
21．The moment we heard the news of the earthquake, we began to ________ the work to rescue those who were trapped in the building.
A．set off
B．set down
C．set aside
D．set about
