We are confident that the environment________by our further efforts to reduce pollution(2013·辽宁，30)

Mr Black is very happy because the clothes made inhis factory have never been

Someone’s knocking at the door. Is it your mother-No, dad. It _____be mom. I saw mom ____in the bedroom just now.

________Alan’s pens –Yes, they’re ________.

I like _____ the piano and I can _____ a bike.