两个完全相同的梯形一定可以拼成一个( )形,这个图形的底等于( )。每个梯形的面积等于拼成图形面积的( )。
平行四边;梯形的上下底之和;
I hope that ______ that I’ve been able to do is of some use to you.
A.a few
B.the few
C.a little
D.the little
用低熔点材料粘结装夹工件,可以减小工件的受热变形。( )