C.never D.often
12.A.prospect B.way
C.reason D.necessity
13.A.primary B.first
C.principal D.prior
14.A.tips B.mouth
C.lips D.tongue
15.A.besides B.and
C.or D.but
16.A.hear of B.attend
C.hear from D.listen
17.A.former B.formula
C.formal D.formative
18.A.theme B.topic
C.idea D.point
19.A.border B.link
C.degree D.extent
20.A.diversion B.distinction
C.diversity D.similarity