根据句意，写出括号内所给单词的适当形式。
Henry and his parents go to visit his grandparents ________ (two) a month.
It’s a ________ (real) cold day. You’d better put on more clothes to keep yourselves warm.
The watch on the table may be one of the football ________ (play).
Please write down your ________ (hobby) on the paper, children.