the operation proved to be very difficult.it proved to be ___operation1 the difficult 2 a difficult选择哪一个,为什么
问题描述：
the operation proved to be very difficult.it proved to be ___operation
1 the difficult 2 a difficult
选择哪一个,为什么
答
a difficult 不能用the 特指
答
it proved to be ___operation
a difficult 一个比较难得操作,不能用the 特指