1.First published in 1927, the charts remain an _______ source for researchers.
　　A intelligent
　　B indispensable
 　　C inevitable
　　D identical
　　
2. Please___ dictionaries when you are not sure of____ word spelling or meaning.
　　A search
　　B seek
　　C inquire
　　D consult
　　
3. It ____ you to at least 50% off the regular price of either frames or lenses when you buy both.　　
　　A credits
　　B entitles
　　C presents
　　D tips
　　
4. The __ at the military academy is so rigid that students can hardly bear it.
　　A confinement
　　B convention
　　C discipline
　　D principle
　　
5. Doctors warned agaisnt chewing tobacco as a _____ for smoking.
　　A succession
　　B substitute
　　C revival
　　D relief