2^0 = 1 无法解释··2^1 = 22^2 = 4 2乘以2=42^3 = 8 2乘以2乘以2=4乘以2=82^4 = 162乘以2乘以2乘以2=162^5 = 322乘以2乘以2乘以2乘以2=32