rock floor的用法和樣例：
例句
- Chunks of the overlying rock may break off and become a part of a sill.
上復巖石的碎塊可能破裂并成為巖床的一部分。 - In fact, this period of Canada's underground rock Chuangpi area of great scientists of the Earth's surface known as the oldest known.
事實(shí)上，加拿大的這段地下面積很大的巖床被科學(xué)家稱(chēng)之為地球表面已知的最古老的地方。
