bed; layer; stratum; coat.
A surface stratum
class; course
My daughter got the best/highest/top mark (s) in the class
It's a present from the whole class
Which/what class is he in?
To sit at the front/back (row) of the class
Most of the teaching is done in the morning
form; grade
The 9th form is the last of a junior high school
In the upper/lower forms
(động vật học) class
The class of mammals
act
A play of three acts