填运算符号.
问题描述：
填运算符号.
3()3()3()3=1
3()3()3()3=2
3()3()3()3=3
3()3()3()3=8
答
3(x)3(÷)3(÷)3=1
3(÷)3(+)3(÷)3=2
3(x)3(-)3(-)3=3
3(x)3(-)3(÷)3=8