He could not have known what was in the letter ___ he had written it himself.
A.until    
B.unless
C.if
D.if only

Ever ___ they came to live here, they have hated everything about this place.
A.since   
B.when
C.though
D.if

___ you work harder, you are going to fail your exams.
A.if
B.because
C.although
D.unless

The road will remain safe ___ the flood washes out the bridge.
A.unless
B.as long as
C.providing that
D.since

I was about to accept his offer ___ my brother told me that he was a notorious liar.
A.since   
B.so
C.then    
D.when

I am not against the plans for the new gallery at all; ___ I think it’s a marvelous idea.
A.on the other hand
B.on the contrary
C.in contrast
D.nevertheless

It was not ___ midnight that they discovered the children were not in their bed.
A.until    
B. at
C.during
D.when

___ the problems are numerous, we must still try to solve them.
A.in spite of
B.although
C.in order that   
D.since

“You can’t have this football back ___ you promise not to kick it at my cat again”, the old lady said firmly.
A.while
B.until    
C.when
D.though

Some fish can survive only in salt water, ____ other species can live only in fresh water.
A.since   
B.unless
C.if
D.whereas