He umpired baseball games.他担任棒球比赛的裁判。He umpired in the tennis match.他在网球比赛中担任裁判.I’ve umpired a cricket match for them.我当过他们的板球比赛的裁判。He umpired for school football matches until he was in his late 50s.他担任校际足球比赛的裁判一直到年近花甲。...
Old buses are major contributors to pollution in British cities...破旧的公交车是造成英国城市污染的主要因素。Resonance theory says that benzene can be represented by two contributors.共振论认为苯能用两个参与体表示.Large public and private companies have lon...