孔型的构成通常由锁口、孔型的侧壁斜度、孔型的内外圆角、()和辊环五部分组成。
参考答案:辊缝
___we can’t understand is ____he didn’t join us in our discussion.
A.That; why
B.Which; how
C.What; what
D.What; why
谈谈杜甫对中唐诗坛的影响。