a和b都是小于20的奇数，要使ba是一个最大的真分数，则ba=1719；
故答案为：1719．
A(n)_______ of 10,000 dollars was _____ to anyone who could provide any clues leading to
the catch of the criminals who tried to murder the president. [ ]
A. award; offered
B. reward; given
C. prize; provided
D. reward; offered
正己烷的废液如何处理？
tried to murder the president. [ ]