Task: Question Answering
Input (English): Context : PetroChina Company Limited (simplified Chinese: 中国石油天然气股份有限公司; traditional Chinese: 中國石油天然氣股份有限公司; Uyghur: چوڭگو نېفتى‎) is a Chinese oil and gas company and is the listed arm of state-owned China National Petroleum Corporation (CNPC), headquartered in Dongcheng District, Beijing. 
Question : Which company is the parent company of PetroChina?
Output (English): China National Petroleum Corporation