离心式压缩机转子在临界转速附近转动时所表现出来的现象是（）。
A、轴向窜动
B、流量降低
C、压力降低
D、振动加剧
参考答案：D
下列关于“四项基本原则”说法正确的是（ ）
①四项基本原则是我国的强国之路
②四项基本原则是我们党、我们国家生存发展的政治基石
③四项基本原则是我国立国之本
④坚持党的基本路线不动摇，关键是坚持四项基本原则
A．①②
B．②③
C．①③
D．②④
For periods beginning on or after l January 2011, the Global Investment Performance Standards () require that total firm assets be defined as the aggregate fair value of all:（）
A. discretionary assets in fee-paying portfolios managed by the firm.
B. discretionary and non-discretionary assets in fee-paying portfolios managed by the firm.
C. discretionary and non-discretionary assets in fee-paying and non-fee-paying portfolios managed by the firm.
) require that total firm assets be defined as the aggregate fair value of all:（）