On a visit to England, Wendy saw a car accident and the police officer asked her some questions.
The police officer asked her1she had seen the accident happen. She said “yes”. She was 2to go across Green Street at that time. And the 3asked her where she was standing. Wendy told him that she was 4the south side of Green Street, near the corner. She wanted to 5to the north side of Green Street. The police officer asked her what she6. Wendy said that a white car with an “L” sign on it came along Green Street to City Road. It did not 7at the traffic light. That surprised her very much. The driver was a man with a woman sitting beside8. He drove straight out into City Road without 9left and hit a yellow car which was going to the north. Then both10crossed the road and went into the street about 20 meters away. They finished up on the east side of City Road.
The policeman said thanks to Wendy and asked her name and address.

①从当地（甲地）和另一无污染的水源地（乙地）分别取等量的水．

②从乙地同一地点取同一批蛙的卵块，分别将相等数量的卵放入甲地和乙地的水中培养．甲地的水设置为甲组，乙地的水设置为乙组．

③甲、乙两组分别设置了三个重复实验组．

④分别进行培养和观察记录，发现甲组蛙（三组）还是三条腿，而乙组蛙（三组）正常，是四条腿．

根据以上实验，回答问题

根据图画内容和所给提示词语，写出完整的句子。

从1985年开始，我国陆续在内地20个省、市 开办了西藏班、新疆班等少数民族班。20多年来，为少数民族地区培养输送了大量各类人才。在内地开办民族班（）
①有利于国家稳定和民族团结
②有利于促进少数民族地区经济和社会的进步
③是发展社会主义民主政治的重要表现
④是保障少数民族地区人民享有教育平等权的重要途径