To live a green life, we try_________ more energy and produce less pollution.

The baseball is _____ the floor _____ the desk.[ ]

Can you take photos with elephants? —- Certainly. ______ elephant is ______ useful animal. I like them.

I missed the beginning of ________musical programme The Voice of China. —What a pity! You should leave school half _______ hour earlier.

Some scientists believe that there will be more robots inyears.