这个句子怎么连接好？

第一句的时态是现在时,跟后面过去时不搭配.
还有,最后一句应为"虽然...但是"结构,逻辑上有些问题,最后修改如下:

During my work，I was in charge of the software developing section and at the same time sent to take part in IMS,a network system,in which I've done a lot,from taking notes to testing systems.Though that's indeed a heavy burden,I've developed precious working experiences.

I am in charge of developing software at my work. I was sent to take part in developing a network system called IMS. My duty in this project ranged from writing text to testing system. Because of the heavy workload, I developed my work experience....

I am in charge of developing software during my work.(表示事实 就用一般现在)I was sent to take part in IMS which is a network system.In this project，my duty ranged from writing text to testing system。I have developed work experience with the heavy workload.