VOA慢速英语:American History Series: President Lincoln is Shot at Ford's Theater

be of no importance=be+形容词=be important

2.From so horrible a beginning, what might come next. How far would the bloody work go.

so horrible a beginning,非常可怕的开始，相当于such a horrible beginning

3.That is the time of year when lilac plants burst into flower throughout much of the United States.

burst into闯入,开出,突然出现

例句：The audience burst into simultaneous applause.
      观众齐声叫好。