1.D. When the ceiling fan works in any gear, the downward wind will generate upward reaction force, so that the ceiling fan is subjected to three forces, namely upward tension+upward reaction force = downward gravity. So choose D.

2.c. This is a question of choosing a reference system. If they are all based on the ground, they are obviously displaced from the point of view of facts, but Beidou and Polaris are very far from the earth and can be ignored. But from the observer's point of view, Polaris is in the direction of the earth axis, and no displacement change can be observed, while the Big Dipper rotates along the earth (observer's point of view). So choose C.