阅读理解，判断正误。

Four Seasons

    Spring is the best season of the year. It lasts from March to May. The days get longer. The nights get shorter, and the weather gets warmer. Everything begins to grow. Grass and trees begin to turn green. Flowers begin to come out. Children begin to fly kites outdoors.

    Summer comes after spring.  It is the hottest season in the year. It lasts from June to August. People try to find a cool place then. They always go swimming in pools, lakes, and rivers.

    Autumn is the harvest season. It gets cool. Farmers begin to reap (收割).They are busy from September to November.

    The coldest season of the year is winter. It's from December to February. The days are short and the nights are long. It snows sometimes and that makes the children happy. They make a snowman and dance around it. They go ice-skating as well.

如图1，有一张矩形纸片ABCD，已知AB=10，AD=12，现将纸片进行如下操作：现将纸片沿折痕BF进行折叠，使点A落在BC边上的点E处，点F在AD上（如图2）；然后将纸片沿折痕DH进行第二次折叠，使点C落在第一次的折痕BF上的点G处，点H在BC上（如图3），给出四个结论：

①AF的长为10；②△BGH的周长为18；③ $\frac{BG}{GF}$ = $\frac{2}{3}$ ；④GH的长为5，

其中正确的结论有____．（写出所有正确结论的番号）