I often take part in my school's activities.
我经常参加学校的活动
What‘s your favorite activity?
My favorite activity is swimming.
你最喜爱的活动是什么?
我最喜爱的活动是游泳.
The oceans froze over when geologic activity died out.
这些海洋在地震活跃带消失时也会冻结.
Whether this translates into real activity remains a question-mark.
它能不能转化为实际行动还不好说.
后两句较难.希望可以采纳.