(2-1/2+2)*2=7分步:1/2=0.52-0.5=1.51.5+2=3.53.5*2=7
2/2=12*2=42+1=33*1+4=7
2+2+2+2-1=7
题有问题2的4次方除2减1
(2-1÷2+2)×2=7
2*2*2-2+1=7