at the trial 特指某次庭审,是相对于其他次庭审而言的；in a trial 指某次具体的庭审,强调的是过程.例如：New evidence showed the suspect lied at the trial.新的证据表明,嫌疑犯在审讯时撒了谎.意思是指：嫌疑犯...