短语词组短语king bolt bush head 中柱的大头bolt square head 方头螺栓BOlT CYLINDER HEAD 气缸盖螺栓bolt hexagon head 圆头螺栓cup -headed bolt snap head bolt 半圆头螺栓bolt head recess 弹底槽bolt head surface 螺栓头表面Bolt -flange head 法兰头螺栓 返回 bolt head