壳相
参考答案：多由具有厚重外壳的底栖生物：腕足、双壳、腹足、三叶虫等密集堆积形成的生物相称为壳相。
小题1:I want to travel, e______________to English-speaking countries.
小题2:Keeping p__________, such as dogs and cats is more and more popular among young and old.
小题3:Have you ever h_______________ of the interesting story?
小题4:Would you m_______________ turning down the music?
小题5:He has been c________________ stamps for five years.
禁牧和休牧有哪些好处？
