A true friend is a person ________ will always be there to share your laughter and tears.
what
which
who
whom
Mike wants to be a policeman. He thinks it is a good ______.
The weather ______ hot tomorrow.
In the future, robots will ______ help people do many things, such as washing and cooking.
Is it cheap ______ from Qingdao to Beijing by train?
What will the weather ______ the day after tomorrow?