One of China's state-owned oil companies may still be smarting from its failure to acquire Unocal this summer. But another Chinese oil giant showed on Monday that this country is still snapping up assets to satisfy its hunger for energy. 1 S$ b$ s- \+ d: e" Y China's biggest state-owned oil company, the China National Petroleum Corporation, announced on Monday that it would pay $4.18 billion for a Canadian oil company with shares traded in New York and substantial reserves in Kazakhstan. 1 L7 h% K0 I& l. Y It is China's largest foreign acquisition yet, and more than twice what a Chinese computer company paid for I.B.M.'s personal computer business.