The librarian told me that I could ___ these magazines for three days.
A:borrow
B:buy
C:keep
D:return
小数每相邻两个计数单位之间的进率都是10。
若函数f(x)=3x﹣1的反函数为f﹣1(x),则f﹣1(1)=____
② (3−2)2+(3+2)2 .