---______ the farmers discovered the entrance to the secret cave in the valley?
--- Totally by chance.
A. When was it that B. How was it that C. How it was that D. When it was that
One more month, _______ the grapes in the yard will be ripe.
A. or B. otherwise C. but D. and
_______these coins are of different shapes, sizes and colors, they all date back to a long, long time ago.
A. Since B. Unless C. Once D. While
When _______ about their opinion of the effect of modern equipment on their performance of tasks, many young people gave a positive response.
A. asked B. asking C. being asked D. to ask
-----Have you heard the amazing news?
-----But it _______ be true. Anyone with common sense won’t believe it.
A. mustn’t B. can’t C. may not D. shouldn’t
All 5 children of the Blacks, _______ are now working abroad, will come back for their parents’ 50th wedding anniversary.
A. two of whom B. two of them C. both of whom D. both of them
