我知道数学课不受欢迎。
I am sensible of the fact that mathematics is not a popular subject.
令人惊讶的是，数学课被选为他们最喜欢的科目。
Surprisingly, mathematics was voted their favourite subject.
他讲数学课。
He gives lessons in mathematics.
How many subjects are you taking this year?
你今年修多少门课？
How many times do I have to tell you not to do that?
我得跟你说多少回不要做那种事？