With an appropriate preposition:
(1)His father will be back from London ____ a few days.(2) ____ hearing the good news, they jumped with joy.
【正确答案】：in;On
【题目解析】：【考点点击】本题考查介词。【要点透析】in+时间段表示从现在起一段时间之后。on(ones)doing意为“当…时”,相当于when引导的时间状语从句。如:On(my) asking for information, I heard a loud noise outside.
