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

Dear Mary,

I receive your E-mail just now. Don’t worry about me. I’m getting on well with my research work in the lab. But to my greatly surprise you say you will give up learn English. The reason is because you have not done well in it recently and you have lost interests. I’m afraid I couldn’t agree with you . I know it is difficulty to learn English, and English is widely used in the world today. It will be important tool in our future work. Beside, it is becoming more and more important in our daily life. If you study hard, you will be succeed. Do remember that where there is a will, there is a way. I’ m looking forward to hearing good news from you.

Yours,

Li Hua

管子焊接的质量控制要点是什么？