(2) Wheat is the main food crop in the north, and rice is the main food crop in the south.
(3) South China is rich in hydropower resources, and the power industry is dominated by hydropower.
(4) Yak is a representative animal in Qinghai-Tibet region, and it is called "the ship on the plateau".
(5) Northwest China lives inland, far from the ocean, with little precipitation, and the main feature of the natural environment is drought.
(6) Heilongjiang Province is located in the northern region.
Therefore, the answer is: (1) North; South; (2) wheat; (3) hydropower; (4) yak; (5) drought; (6) the north.