trial可数吗

trial是可数的。
trial：
v、试验;试用;测试(能力、质量、性能等)
n、(法院的)审讯，审理，审判;(对能力、质量、性能等的)试验，试用;预赛;选拔赛
复数： trials

Many drugs were found by trial and error

很多药物都是通过反复试验才发现的。

We plan to release a prototype this autumn for trial in hospitals、

我们计划今年秋天在各医院推出一个模型进行试验。

The system was introduced on a trial basis for one month、

这个制度已引进试行一个月。

The date of the trial has been advanced by one week、

审判日期提前了一星期。

The trial is expected to continue for three months、

预计审判要持续三个月。