英语语法分析

Roughen the surface before applying the paint.

先把表面弄毛糙再涂颜料。

By sanding the split leather surface to roughen it up.

是通过打磨分割层皮革的表面，使它变粗糙而得到的。

You'd better roughen the surface before applying the paint.

你最好先把表面弄毛糙再涂颜料。