18、The teachers want to (do away with) cheating in their school.
A.put an end to
B.retain
C.do credit to
D.substitute for
19、The mail was (delayed) for two days because of the snow-storm.
A.held in
B.held up
C.held down
D.held off
20、He is always (under the weather).
A.travelling
B.sick
C.away
D.unconscious
参考答案：1 D 2 B 3 A 4 B 5 B 6 D 7 B 8 D 9 C 10 C 11 A 12 C 13 A 14 D15 C 16 C 17 C 18 A 19 B 20 B