1. After a few weeks' experience, apprentice jewelers can usually begin to discriminate, though not with absolute certainty, genuine diamonds from imitation diamonds.

　　(A) genuine diamonds from imitation diamonds

　　(B) genuine diamonds apart from imitations

　　(C) between genuine diamonds and imitation diamonds

　　(D) among genuine diamonds and imitation diamonds

　　(E) whether diamonds are imitation or genuine

　　2. Convinced at last of the soundness of her advice, the villagers tried crop rotation, built crude sanitary facilities, and even the use of goat's milk for the making of cheese.

　　(A) the use of goat's milk for the making of cheese

　　(B) used goat's milk to make cheese