Complex sentence: The construction of the West-East Gas Pipeline started in 2002 and it was put into trial operation on 1 October 2004and the full line commercial supply of natural gas commencee on 1 January 2005.
Split into simpler sentences: The construction of the West-East Gas Pipeline started in 2002. The pipeline was put into trial operation on 1 October 2004 and the full line commercial supply of natural gas commenced on 1 January 2005.