She heard a song____ was full of feelings of happiness.( )
which
who
what
— Hello, Jack. ______ are you? —Fine, thank you.
The girl is Mary Smith, and her last name is ______ .
My uncle is an actor. His job is at a _________.
There _______ a pen on the desk. It is a black pen.
—Mum, my teacher, Mr. Wang. — Nice to meet you, Mr. Wang.