若f(x)x^(2^n-1)-1,则属于a的一个周期是()。
A、2^n+2
B、2^n+1
C、2^n-1
D、3^n
参考答案:C
After they married, they decided to move back to the village and _______. [ ]
A. bring down
B. calm down
C. put down
D. settle down
收缩率的影响因素有压力、温度和()。