A low-carbon(低碳) lifestyle has an effect our daily life. People are paying more and more attention to energies these days.
The lovely room might be_________.
Who’s that boy reading in the garden? Is it David? ----It______be David. I saw him in the classroom just now.
She _____________ Beijing when she _________.
--- Don’t forget _____________ the door when you leave the classroom.
_______________ do we need ?