They like to fly a kite in the summer中,为什么要用To fly

like to do 是指一时的打算,有“愿意”的意思,与would like to do 有相似意思like doing 是习惯性的,有种喜欢的倾向比如说,i like apple pies but i dont like to take a second one 我喜欢苹果派（一直喜欢,习惯性的倾向）,不过我不想再吃了类似有法还有 be afraid to do (一时的心理）,be afraid of doing （习惯性的害怕）i am afraid of doing out in the dark 。我一直都害怕走夜路i am afraid to go across such a bridge which is damaged so much 我怕过怎么破的桥（就那时怕,可能就在过桥前,而且不是每次遇到的桥都这么破的）明白了吗