可否列出可能性呢？

Xiaotongdi

A photographerwill arrange 6 people of 6 different heights for photograph by placing them in two rows of three so that each person in the first row is standing in front of someone in the second row.The heights of the people within each row must increase from left to right, and each person in the second row must be taller than the person standing in front of him or her.How many such arrangements of the 6 people are possible?


A.5
B.6
C.9
D.24
E.36
这类题要列出所有可能性？还是用什么公式？

Xiaotongdi

有没有人帮下忙解救！

oceantaferia

列出所有可能喽！通常这类题答案不会太多个。
123     124     125     134     135
456     356     346     256     246

共5个