题目

One cold night, after attending a birthday party, Ann walked home along the quiet road．Suddenly from the shade of a dark building, a tall man with a knife in his right hand ran out at her and then said in a cool voice, Give me your earring or you will die． Hearing this, Ann seemed less worried, and after a minute, she became calm．She tried to cover her necklace with the collar （领子） of her overcoat．She wanted to make the robber think she cared for the necklace than for the earrings．Then she used the other hand to take off both of her expensive earrings, which she quickly threw关于黑土的利用，下列叙述正确的是 ［　　］ A．建设商品粮基地，以保持黑土较高的生产力 B．加强对坡面、沟壑的治理，以提高土壤肥力 C．注意土壤培肥，以避免土壤冲刷 D．秸秆还田是近年来保持和提高黑土肥力最有效的办法