如图，⊙O中，弦AB等于半径OA，点Ｃ在优弧AB运动上，则∠ACB的度数是（   ）

①各民族结成了平等、团结、互助、和谐的社会主义新型民族关系②坚持了民族区域自治制度③坚持了***的领导④各民族经济地位实现平等，民族差别已经消除

根据短文内容，判断正确还是错误。

    I'm a junior high school student. My name is Sarah. I have a pretty aunt. Her name is Jenny. She is an actress. She must be at least thirty-five years old. In spite of this, she often appears on the stage as a young girl. Jenny will have to take part in a new play soon. This time, she will be a girl of seventeen. In the play, she must appear in a bright red dress and long black stockings. Last year in another play, she had to wear short socks and a bright, orange-coloured dress. If anyone ever asks her how old she is, she always answers,“Darling, it must be terrible to be grown up!”This is my lovely aunt. I love my aunt.

下列成语中，哪个说明了生物能够影响环境的道理（　　）