在易燃易爆生产场所穿化纤工作服会产生静电火花，容易引起火灾或爆炸。
参考答案：对
The research is so designed that once ____ nothing can be done to change it.
A．begins
B．having begun
C．beginning
D．begun
比较铸钢与轧制钢材的性能特点？
