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20. It takes a long time to restore nature _______ it is damaged.A. since B. unless C. once D. until21. “You can’t judge a book by its cover,” __________A. as the saying goes B. goes as the old sayingC. as the old saying goes D. goes as old the saying22. Are my clothes too casual?No. you can go ______you are.A. as B. what C. that D. where23. The teacher told us not to take the equipment out of the lab until _______A. allowed to B. allowing to C. allowed to be taken D. allowing to takeDCDDA DBBADC ADACADAB CCAA。 whom C. what。 whom B. wh