根尖的结构包括根冠、分生区、伸长区、成熟区四部分，成熟区有大量的根毛．下列有关叙述正确的是（　　）

若代数式（2x+1）²的值为9，则x的值为（）

“长征5号”火箭于2016年11月3日20时43分在文昌卫星发射中心成功发射升空，成为中国运载能力最大的火箭．“长征5号”火箭点火升空时，经过3s速度达到45m/s，设火箭上升可看作匀加速运动，

下列说法中正确的是(　　)

阅读下列短文，从每小题的三个选项中选出最佳选项。

    It's autumn. It's cool and windy. Charlie is flying a kite in the park. His father is watching(观看).The kite is flying high(高) in the sky. They are happy. Look! The kite is not in the sky now. Where is it? Oh, it's in a tree. Charlie is sad. Charlie jumps and jumps. The tree is tall but he is short. He cannot get(拿到) the kite. Charlie's father is not very tall but he is clever(聪明的). Look, he is on a car. He can get the kite for Charlie. Charlie is happy.