Complex sentence: She was the first sitting member of Parliament to be killed since Ian Gow was killed by the Irish Republican Army in 1990, and the attack was the first serious assault on an MP since Stephen Timms was stabbed by Roshonara Choudhry in an attempted assassination in 2010.
Split into simpler sentences: She was the first sitting member of Parliament to be killed since Ian Gow was killed by the Irish Republican Army in 1990. The attack on Cox was the first serious assault on an MP since Stephen Timms was stabbed by Roshonara Choudhry in an attempted assassination in 2010.