请根据下面提示，写一篇短文，词数不少于50.

In your spoken Endlish class, your teacher shows you the following picture. You are asked to describe the picture and explain how you understand it.

影响切削力的因素有（），切削用量和刀具角度

A.工件的大小

B.工件材料

C.工件韧性

D.工件的成分