飞行器降落停稳后如何关闭电机（）
A、油门指令↓+F滑杆↑
B、油门指令↑+F滑杆↑
C、油门指令↓+F滑杆↓
D、油门指令↑+F滑杆↓
参考答案：C
Beijing opera is popular with lots of people in Beijing, but it is not to everyone's _____ in
other parts of China. [ ]
A. smell
B. favor
C. sound
D. taste
乙醇中检查杂醇油是利用：
A．颜色的差异
B．旋光的差异
C．臭味及挥发性的差异
D．对光选择吸收的差异
E．溶解行为的差异
