A.As long as
B.Whether
C.Unless
D.Even if

A.front
B.above
C.over
D.ahead

A.front
B.above
C.over
D.ahead

A.face
B.deal
C.encounter
D.challenge

A.refusal
B.question
C.challenge
D.obstacle

A.influencing
B.determining
C.controlling
D.pointing

A.as difficult as
B.so difficult as
C.more and more difficult
D.most difficult

A.I'm doing
B.I do
C.I did
D.I have been doing

A.it was
B.it will be
C.it's
D.it would be

A.think
B.are thinking
C.are thought
D.have thought