简述虚拟现实技术的主要特征。
参考答案：
交互性、沉浸性、想象性。
I know one of the things _____I was unsure about was _____ hard it would be to climb this mountain.
A．that; how
B．what; how
C．which; what
D．/; what
贷款种类可分为（）。
A、信用贷款
B、自营贷款
C、委托贷款
D、特定贷款
