you smile at others,they will smile back.
I sent ______ e-mail to Amy to say thanks for her help with my study.
—Nancy, would you mind turning down the music? Your father is writing his report. — .
---You are late again. The class ________ for five minutes. ---Sorry. There is something wrong with my bike.
_______ the mouse, you can choose an icon _______ for more details.
----Look at the boy running on the playground. Is it David? ---- It ______ be him. I saw him go to the teachers’ office just now.