题目

  The largest bird that cannot fly also happens to be the largest living bird in the world. This is the huge North African ostrich (鸵鸟). When the male is fully grown, he reaches a height of nearly eight feet and many weigh close to three hundred pounds. His wings are very small and the wing feathers are very soft, and therefore he does not fly. You have probably heard the old saying about “the foolish ostrich burying his head in the sand”. Well, the ostrich is not nearly as foolish as he is said to be. In the daytime, when the hen is sitting on the eggs, she does not want to b已知下列单细胞生物,它们都具有细胞壁,但没有核膜和核仁,在研究它们 生活所需条件的实验中,得出下面的结果(√表示需要)。这三种生物依次是 生物必需的生活条件水氧CO2葡萄糖氨光A√√√√B√√C√√√√A.衣藻、乳酸菌、变形虫 B.衣藻、酵母菌、变形虫 C.固氮蓝藻、酵母菌、硝化细菌 D.固氮蓝藻、乳酸菌、硝化细菌
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