I find _____ difficult for us to master English if we don’t work hard.
It's __________ comfort to know there is someone to keep __________ eye on the kids.
Now what we need is something __________ will make human beings live better.
—Would you like to play bridge with us? —Sorry. __________.
Please let me know __________ you want to go or not.
It took __________ building supplies to construct these energy-saving houses. It took brains, too.