Grade 6 (Lower). Elementary School Students Mental Arithmetic Practice Book

Author: Zhang Hui
Publisher:
Publish Date: 2002-10-01
Features: Coral is a carnivorous animal living in the ocean, with common types being staghorn coral and gorgonian coral. Coral is divided into soft coral and hard coral, both of which are formed by countless coral polyps. Coral islands and reefs in tropical oceans are made up of skeletons secreted by coral polyps. Coral can be used to burn lime, make cement, build houses, pave roads, or serve as a natural repository for generating and storing oil and natural gas.