a…だけ, …の差で‖escape by a hairbreadth 間一髪のところで助かる/miss the train by five minutes 5分のところで汽車に乗り遅れる/The number of the committee members should be cut by half. その会の委員は半分に減らすべきである/He is older than Jane by two years. 彼はジェーンより2歳だけ年上だ(＝He is two years older than Jane.)《◆後者の方が普通》.