TPO20阅读求助

zcy07UID: 2538317

第二篇第21题
做的时候就在AB之间徘徊
虽然知道A没说全但考虑到B有个already existing fossil structure所以没选B，但答案是B，为什么啊，原文也没说permineralization加固了已经存在的化石结构啊

zcy07UID: 2538317

Many other processes may after the shell of a clam or sanil and enhance its chances for preservation. Water containing dissolved silica, calcium carbonate, or iron may circulate through the enclosing sediment and be deposited in cavities such as marrow cavities and canals in bone once occupied by blood vessels and nerves. In such cases, the original composition of the bone or shell remains, but the fossil is made harder and more durable. This addition of a chemically precipitate substance into pore spaces is termed permineralization.

which of the following best explains the process of permineralization mentioned in paragraph 3
A. Water containing calcium carbonate circulates through a shell and deposits sediment.
B. Liquid containing chemicals hardens an already existing fossil structure

sennilUID: 3137408

the original composition of the bone or shell remains,=an already existing fossil structure