Complex sentence: Sihanouk spent most of his time in Beijing for medical treatment, but made a final public appearance in Phnom Penh on his 89th birthday and 20th anniversary of the Paris Peace Accords on 30 October 2011.
Split into simpler sentences: Sihanouk spent most of his time in Beijing for medical treatment. He made a final public appearance in Phnom Penh on his 89th birthday and 20th anniversary of the Paris Peace Accords on 30 October 2011.