He died, literally , at the chalkboard at age 83.他過(guò)世了, 83歲的時(shí)候, 在黑板前.Then one morning we were working math problems at the chalkboard.后來(lái)有一天早晨,我和瑪麗在黑板上寫(xiě)下了數(shù)字題目.The map was drawn on chalkboard with ink - markers.那張地圖用記號(hào)筆畫(huà)在一塊...