---Do you feel like ______ or shall we go by bus?

---I prefer _______ , but we had better take a taxi, for time is short.

A．to walk; walking

B．walking; to walk

C．walking; walking

D．to walk; to walk

本题的功能是求1～100的自然数的累加，并打印输出计算结果。
public class java1
public static void main(String[] args)
int sum=0;
int i=l;
for(;;)
if(______)
sum=sum+i;
else
______;
______;

System. out. println("sum="+sum);