on trial
1.受审being judged
He is on trial for murder.他因谋杀而受审。
2.在试验〔测试〕中being examined and tested
He is employed for two weeks on trial.他被雇来试用两周。
trial and error
反复试验,从失败中找到解决办法process of solving a problem by trying various solutions and learning from one's failures
They didn't know how to put in a central heating system, but they managed it by trial and error.他们不知道怎样安装集中供暖设备,但是经过反复试验终于安装好了。