东南亚主要的热带经济作物主要有[ ]
A．天然橡胶、油棕、椰子
B．天然橡胶、油棕、水稻
C．油棕、椰子、咖啡
D．油棕、水稻、棉花
答案：A
The 29th Olympic Games, in Beijing in 2008, was a great success. [ ]
A. to play
B. played
C. playing
D. to be played
通常在整定调节器参数时，应把（）放在首位。
A.快速性
B.稳定性
C.准确性
D.灵敏性
