显示特定引导手信号时，昼间为展开的绿色信号旗（）。
A、左右摇动
B、高举头上左右摇动
C、上下缓动
D、左右缓动
参考答案：B
To some people, happiness is __________ by family and friends, while to others, it means ___________ success.
A．being surrounded ; achieving
B．being surrounded ; to achieve
C．to surround ; achieving
D．surrounding ; to achieve
地面对入射太阳辐射的反射取决于地面的反射率（r），而r又取决于（）。
