长难句一
One of the earliest epidemics on record happened about 500-550 AD when the Roman emperor at the time was attempting to rebuild the Roman Empire.
【句式翻译】历史上有记载的最早的传染病之一发生在公元500-550年，当时的罗马皇帝正在试图重建罗马帝国。
【句式分析】本句包含一个when引导的限制性定语从句，从句中运用了过去进行时。
【词语点拨】attempt v./n.尝试，试图
William attempted to find the solution to the problem.
威廉试图找到问题的解决办法。
He was nearly drowned in the attempt to swim across.
他在试图游到对岸去时差一点被淹死。
【语法点拨】过去进行时的构成：was/were doing，表示“过去某个时间正在进行的动作”。常用的时间状语有this morning, the whole morning, from nine to ten last evening, when, while等。如：
What was he writing all day last Sunday?
上周日他一整天都在写什么?
My brother fell while he was riding his bicycle and hurt himself.
我哥哥骑自行车的时候从车上摔下来受伤了。