1. As a defense against air-pollution damage, many plants and animals_________ a substance to absorb harmful chemicals.
　　A. relieve
　　B. release
　　C. dismiss
　　D. disclose

　　2. As a matter of rule, the scrap value of a vessel can hardly be at ________ with the sound value.
　　A. par
　　B. bearish
　　C. collapse
　　D. rally

　　3. As a salesman, he works on a (an) ________ basis, taking 10% of everything he sells.
　　A. income
　　B. commission
　　C. salary
　　D. pension

　　4. As all of us know, color-blind people often find it difficult to ________ between blue and green.
　　A. separate
　　B. distinguish
　　C. compare
　　D. contrast

　　5. As everyone knows, the exchange ________ fluctuates almost daily.
　　A. ration
　　B. ratio
　　C. rate
　　D. interest

　　6 As far as the rank of position is concerned, an associate professor is ________to a professor, though they are almost equally knowledgeable.
　　A. attached
　　B. subsidiary
　　C. previous
　　D. inferior

　　7. As I was just getting familiar with this job, 1 had_________ to ask my boss.
　　A. many
　　B. most
　　C. much
　　D. more

　　8. As is well-known, knowledge is the __________condition for expansion of mind.
　　A. indispensable
　　B. indefinite
　　C. inevitable
　　D. impossible

　　9. As scheduled, the communications satellite went into _________ round the earth.
　　A. circle
　　B. orbit
　　C. path
　　D. course

　　10. As soon as it started to rain we turned round and _________ home.
　　A. made for
　　B. called for
　　C. cared for
　　D. searched for