﹣What do you usually do after dinner?
﹣I usually watch news on TV for half____________ hour to know about what's happening.( )
A./B.theC.aD.an
在中,内角,,的对边分别是,,,若,,则等于()
若,则等于()
已知(),且,则是()
已知在等差数列中,,公差,,则的值为()
设向量,,且,则的值是()