________ is this? — It is black

He sometimes _____ e-mails _____ his friends. [ ]

What _______ you do if you _______ 5 million yuan?— I’d travel around the world.

The girl began learning the piano _______ the age of four. She is very good _______ it now. [ ]

__________ the bananas to go bad, he preferred to sell them at half price.