Official 18 Lec 1
Question 4 of 6
What was the importance of Schwabe's observations?

A.

They determined the age of sunspots

B.

They established that sunspots appear in cycles

C.

They proved that sunspots were actually on the Sun

D.

They showed the reason that sunspots change their shape

正确答案:B

显示答案
进入答题
00:00
00:00
隐藏原文

译文

精听文本