上课和下课用英语怎么说？

Stand up. 起立
Class begins.上课
Class is over. 下课

上课:
to
attend
class
Relative
explainations:

classes>
class>
a
lesson>
lessons>
take
lessons>
teach>
go
to
class>
Examples:
1.
在上课期间内不要离开学校。
Don't
leave
the
school
precincts
during
school
hours.
2.
她准是暗地里一直在上课。
She
must
have
been
having
lessons
on
the
sly.
3.
不论阶级，种族，性别，人人都可进这所学校上课。
Everybody
can
come
to
this
school,
without
respect
to
class,
race,
or
sex.
4.
因为流行性感冒全校停止上课。
The
school
was
closed
because
of
the
flu.
5.
在孩子们住院期间,
有个私人教师给他们上课.
There
is
a
tutor
to
teach
the
children
while
they're
in
hospital.
下课:
1.
class
is
over
2.
That's
it
3.
dismiss
4.
to
get
out
of
class
5.
to
dismiss
class
Examples:
1.
那些男孩子们渴望下课。
The
boys
were
itching
for
the
lesson
to
end.
2.
下课后，班长把练习册收了起来。
The
monitor
collected
the
exercise
books
after
the
class
was
over.
3.
下课铃响了.
There's
the
bell
for
the
end
of
the
lesson.
4.
老师要他下课后先别走.
The
teacher
told
him
to
stay
behind
after
class.

time for class
class is over
stand up

Class begin
stand up
class is over

Class
begins.
it's
time
for
our
class.
Time
for
our
class.