连词成句，注意大、小写及标点符号

某造船公司年造船量是20艘，已知造船x艘的产值函数为R（x）=3 700x+45x²﹣10x³（单位：万元），成本函数为C（x）=460x+5 000（单位：万元），又在经济学中，函数f（x）的边际函数Mf（x）定义为Mf（x）=f（x+1）﹣f（x）．

《水调歌头（明月几时有）》小序部分交代了（  ）

注意：1）.每处错误及其修改均仅限一词；
2）.只允许修改10处,多者（从第11处起）不计分。
    More and more foreigners like to come to China. Last Friday our school was invited a foreign teacher in our city give a class to the students of Senior Grade Two. We found his class interested. I learned a lot from him. The teacher had a free talk to us with easy English . He spoke slow so that we could understand him well. Sometimes he repeated what we don't understand. My classmates were all active in the class. To his joy, I understood everything the teacher said. And I was able to ask question in English. This class encouraged me very much. I'm sure that until we keep on practising, it will be easy for us to learn speaking English well.

下列实验不能用水浴加热的是