To live a low-carbon life , we must try to save _____ energy and produce ____ carbon .
This pair of jeans ________ them 300 dollars.
Not only he but also his parents _____China for two years .
--Never forget to bring your homework with _______. --__________.
I think your advice is of great ________ to me and it’s _______.
-- Look at that girl. Is it Susan? --No, it _______ be her. She has gone back to her home town .