(15)
A.method
B.order
C.trend
D.system

(17)
A.circumstances
B.occasions
C.incidents
D.situations

(19)
A.special
B.peculiar
C.specific
D.particular

(21)
A.direction
B.aim
C.search
D.view

(24)
A.disconnected
B.withdrew
C.separated
D.parted

(4)______
A.dry up
B.take in
C.lay off
D.open up

(26)
A.turned out
B.came off
C.went out
D.put off

(28)
A.underestimate
B.lower
C.decrease
D.mislead

Many bridges in England were covered with wooden roofs to protect it from rain and snow.
A.rain and snow
B.Many
C.were covered
D.protect it

All nations may have to make fundamental changes in their economic, political, and the technological institutions if they are to preserve environment.
A.changes in
B.the technological institutions
C.have to make
D.to preserve