()being fun and good exercise,swimming is a very useful skill
问题描述:
()being fun and good exercise,swimming is a very useful skill
答
It
这里是独立主格结构,相当于一个状语从句,这里就等于Because/Since it is fun and good exercise,swimming is a very useful skil.
意为:游泳很有乐趣,是个不错的运动,所以说游泳是项很有用的技能.