【单选题】He _____ in the exam. The teacher_____think he _____ his best. [ ]
【单选题】______ several times, the young scientist still kept on making his experiments. A. Having been failed B. having failed C. Though failed D. Because of failure
【简答题】A) had failed B) failed C) attempted D) had attempted
【简答题】If memories failed to fade, ______.