六级They found fossils of microscopic marine plants which suggest that the region was once open ocean not solid ice.
他们发现了微小的海洋植物化石,这表明该地区曾经是开阔的海洋,而不是固体冰。
2010年12月英语六级真题
四级These microscopic layers of deposits containing bacteria are known as biofilms and they are found on most surfaces and objects.
这些含有细菌的微小沉积物层被称为生物膜,它们存在于大多数表面和物体上。
2018年12月大学英语四级考试真题(第3套)
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