请回答：

根据短文内容判断下列说法的正误。

    There are four seasons in a year．They are spring，summer，autumn and winter．Spring is green with flowers．I can plant trees in spring．Summer is hot．I can swim in the sea．In autumn,farmers are busy．I can eat moon cakes and pick apples in autumn．But I like winter best．Winter is cold．Sometimes it snows．I often skate in winter．Sometimes l make a snowman．

下面是有关燕麦实验的示意图，图中所示燕麦胚芽鞘的某些部位纵向插入了云母片。请分析图中a至f的琼脂块中，生长素含量正确的一组是(　 　)

将方程x²+4x-1=0配方后，原方程变形为（   ）