主体部分用英语怎么说？

主体部分

例句

• The body is 90% titanium for ruggedness. 为了实现优良的耐用性，主体部分90％采用钛金属制造。
• The main component of experiment equipment of coherent harmonic radiation in Hefei is optical klystron. 合肥相干谐波辐射实验装置的主体部分是光学速调管.
• The main part of the hospital is pretty dismal but the children's ward is really lively. 医院的主体部分死气沉沉，但是儿科病房却充满生气。
• Give an introduction, followed by the body of the material, then a brief summary. 首先写序言，接下来是内容的主体部分，然后作简短的总结。
• The main body of the church had been turned into a massive television studio... 该教堂的主体部分已被改造成了一个大型电视演播室。