他一再用白垩粉擦他的球杆尖。
海底的沙子比白垩更白
但是很不幸的是，这段迅速的进化过程发生于中白垩纪的一千五百万年间，而这段时期的鲜有化石记录。
"But there were a hundred million years of evolution to play with."
望着……三角龙：从白垩纪的恐龙(新恐龙收集)。
Looking at... Triceratops: a Dinosaur from the Cretaceous Period New Dinosaur Collection.
浅埋藏似能保留具白垩状结构的孔隙。
Study on Strata Mechanical Structure and Support Adaptability of Shallow Seam;
浅埋藏似能保留具白垩状结构的孔隙。
Study on Strata Mechanical Structure and Support Adaptability of Shallow Seam;
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