talk with 例:Grandma talked with her friends yesterday.
如图,△ABC是⊙O的内接三角形,AD是⊙O的直径,∠ABC=50°,则∠CAD= ____.
同一幅等高线地形图上,等高线密集的地方是____ 坡;等高线稀疏的地方是____ 坡。