未经硫化的橡胶分子结构是线型或支链型，硫化的目的是使橡胶分子适度交联，形成体型或网状结构。
参考答案：对
The building ____ will be a hospital. [ ]
A. build
B. to be built
C. being built
D. being building
向二次回路供电的电源，称为操作电源。
