in和during在时间表达上的区别.During the whole winter it never snowed.和It was very hot during the summer.为什么前者的during不能用in代替,而后者却可以用in代替?

in和during在时间表达上的区别.
During the whole winter it never snowed.
和It was very hot during the summer.
为什么前者的during不能用in代替,而后者却可以用in代替?

in注重是某一时间“点” during更强调在某一时间“段”