如图,⊙O的直径CD过弦EF的中点G,∠EOD=40°,则∠DCF=____.
请根据以上信息回答下列问题:
—Hey, turn it off, please! We don't music in the reading room. ——Oh, I'm sorry, sir. I won't do it again.
通电螺线管下方自由转动的小磁针静止后如图所示,请在图中标出螺线管的N、S极和螺线管中的电流方向.