题目

. Luckily, we’d brought a road map without ______ we would have lost our way.     A. it                  B. that      C. this                D. which 答案：D13．列式计算我最棒（1）一个数的$\frac{3}{4}$是57，它的$\frac{1}{2}$是多少？（2）9的倒数乘$\frac{4}{5}$，积是多少？