A.problems and solutions
B.advantages and disadvantages
C.solutions and limitations
D.causes and effects

A.creates
B.presents
C.poses
D.produces

A.mind
B.sight
C.view
D.thought

A.advance
B.danger
C.end
D.vain

A.in
B.from
C.on
D.at

A.
B.
C.
D.

A.do
B.make
C.raise
D.add

A.scale
B.level
C.extent
D.number

A.do
B.see
C.break
D.leave

A.taken
B.did
C.launched
D.made