根据所给动词的适当形式填空，字数不限。
It usually takes Mum half an hour _______ (cook) supper for us.
--Mum, what do you want to eat?    ---What about        (点) some beef and rice?
Where are the boys in our class?  They __________(plan) a football game.
This little boy sometimes practises _________ (play) the piano at home.
The number of the girl students in Class 1 __________(not be) 25,but less than 20.