Complex sentence: In 1954, China adopted a new constitution at the first National People's Congress (NPC); at the Congress's first session, he was elected chairman of the Congress's Standing Committee, a position he held until the second NPC in 1959.
Split into simpler sentences: In 1954, China adopted a new constitution at the first National People's Congress (NPC). At the Congress's first session, Liu was elected chairman of the Congress's Standing Committee, a position he held until the second NPC in 1959.