位于青藏高原上,有“聚宝盆”之称的盆地是( )
Steve's activity on Sunday
In the past
He spent most of the time 1.
He learnt it from his 2 and he is good at it.
Now
He spends at least 3 hours collecting rubbish.
He would like to protect the beach.
①以反核运动为中心 ②参与阶层主要是学生
③具有全球性特征 ④由分散走向统一