a3=3a(a≠0)______.
因为a3=a×a×a=a•a•a,
所以a3=3a(a≠0)是错误的,故答案为:×.
________ in 1936, Harvard is one of the most famous universities in the United States.
A.Founded
B.Founding
C.It was founded
D.Being founded
简述鱼类循环系统的组成。