主减速器的调整项目有（）；（）和（）。
参考答案：轴承预紧度的调整；啮合印痕调整；啮合间隙调整
---- It is generally believed that teaching is __________it is a science.
A．an art much as
B．much as an art as
C．as an art much as
D．as much an art as
After cutting down the tree, they _____ a little boat out of it．
A．went on to make
B．went on making
C．went on with
D．continued
