mǒu
1
some
2
a certain
3
sb or sth indefinite
4
such-and-such
他是大学的学生。
He is a student at a certain university.
人给我寄了一封信。
Someone sent me a letter.
我在国度旅行。
I'm traveling in a certain country.
这个问题发生在地。
This problem occurred in a certain place.
人在电话里告诉我。
Someone told me over the phone.
事发生在昨天晚上。
Something happened last night.