The Great wall is the only one of the buildings on the earth_____ seen from the moon.

A．which is

B．which are

C．that are

D．that is

塑料义齿抛光时，不正确的操作是（）

A.打磨从粗到细

B.从磨光面到组织面

C.不要破坏基托外形

D.随时变换打磨部位

E.从组织面到磨光面