His father enjoys ____ a walk after dinner.[ ]
A. takes
B. take
C. taking
D. to take
答案:C
若以连续掷两次骰子得到的点数m,n分别作为点P的横坐标与纵坐标,则点P落在点集A={(x,y)||x|+|y|≤6且x,y∈Z}内的概率为______.
简述胰岛素、胰血糖素和糖皮质激素在维持血糖水平相对稳定中的作用?