绢英岩化
参考答案：
中-低温热液蚀变作用，各类中酸性火成岩、泥质岩石最易发生。主要由绢云母和石英等组成，常与中低温热液矿床和斑岩型矿床伴生。
The bridge was built in memory of the adventurer who was believed ______ the valley.
A．to have been discovered
B．to discover
C．to have discovered
D．having been discovered
汽轮机的真空严密性试验试验步骤？
