练习：
1.A.internal B.different C.difficult D.widespread
2.A.volume B.length C.extent D.width
3.A.function B.repair C.build D.remove
4.A.durability B.strength C.ability D.property
5.A.ascend B.compact C.collapse D.recover
6.A.shorter B.longer C.simpler D.stranger
7.A.when B.what C.how D.which
8.A.occasionally B.frequently C.specially D.recently
9.A.development B.phenomenon C.formation D.composition
10.A.unless B.until C.after D.before
11.A.findings B.locations C.events D.sources
12.A.delivered B.deposited C.destroyed D.detached
13.A.near B.from C.inside D.over
14.A.prevent B.accelerate C.predict D.detect
15.A.styles B.sites C.costs D.standards