A．平面α与平面β垂直
B．平面α与平面β所成的(锐)二面角为45°
C．平面α与平面β平行
D．平面α与平面β所成的(锐)二面角为60°
参考答案：A
Many developed countries have agreed to help the less developed ones but it remains ________ whether they will take action or not.
A．to see
B．to be seen
C．seeing
D．seen
何谓辩证论治？
