She may not be free today.—___, we’ll have to put the meeting off.

Why not take some medicine ? —Yes, I do.I have taken medicine for a whole week, but it doesn’t seem to ____.

Who’s your best friend Is ____ a boy or a girl—A boy. I often play with _____ after school.

_________the thunderstorm ,they_________ the injured man in time. They felt sorry for that.

____ has helped to protect the environment is worth praising.