来自宋刚的问题
It'sgreatfun___(jump)intotheriverand___(swim)insummer.
It'sgreatfun___(jump)intotheriverand___(swim)insummer.


It'sgreatfun___(jump)intotheriverand___(swim)insummer.
It'sgreatfun___(jump)intotheriverand___(swim)insummer.
It'sgreatfun(tojump)intotheriverand(toswim)insummer.
因为是It's+形容词+todo的形式