单项选择题
A.fopen("filedat","w") B.fopen("file1.dat","a") C.fopen("fiedat","rb") D.fopen("file1.dat","wb")
A.China B.ChinaBeijing C.Beijing D.BeijingChina
A.x[20]=x[1]+x[2] B.x[2]=x[2]+x[3] C.x[0]=x[-1]+x[1] D.x[18]=x[20]-x[2]