函数$y=3\sin x-4\cos x,x\in 0,\mathrm{\pi })$的值域为（    ）

读世界局部地区图，完成下列各题。

    Last year Jeff left school. He came to Guangzhou to find a 1. He went to one company after another company. But no one wanted him. Then he had 2 money. He had to go back to his small town. 3 he came to the station. He 4 very sad and tired. It was very late at night and the station was 5 of people. They were waiting to buy tickets of the last train. He bought the 6 ticket, so he was very happy.

    At that time, a woman 7 a crying baby walked to him. She asked him to 8 her the ticket. He gave her the ticket. He thought they needed it more than he. After the train left, he sat on the bench and didn't know 9 to go. Just then an old man came and said, "Young man, I saw what you did to help the woman. I have a big company. I need a good young man like you. Would you like to 10for me?"

十一届三中全会后，我国把对外开放确定为加速现代化建设的一项基本国策，使我国经济从封闭状态大踏步走向世界。结合所学知识，回答下列问题：
（1）我国最早设立的经济特区是哪几个？
（2）经济特区的设立对我国经济建设产生了怎样的影响？
（3）从我国实行的对外开放中你得到了哪些启示？