题目：下面算式中，两数之积在\frac{2}{5}和\frac{6}{7}之间的是( ). 
选项：
bullet: A
text: \frac{2}{5}× \frac{13}{14}
bullet: B
text: \frac{6}{7}× \frac{4}{5}
bullet: C
text: \frac{2}{5}× 3
答案：B
解析：因为\frac{2}{5}\frac{6}{5}，而\frac{6}{5}>\frac{6}{7}，所以不在\frac{2}{5}和\frac{6}{7}之间，故C错误. 故选B.