Today we 1 only three lessons in the morning. The first lesson is math. It 2 at eight o’clock and finishes at 3 to nine. It is in Room 101. But I don’t like math. Then the second lesson is my favorite 4 —music. It starts at nine o'clock. The 5 lesson in the morning is PE. It starts at ten 6 ten and finishes at five to eleven. We have our lunch at eleven thirty 7 the second floor of dining hall. We have two lessons 8 lunch. Art starts at two and at three o'clock we have a 9 lesson. We can learn a lot of knowledge about China. At about four in the afternoon 10 is over.

关于卢瑟福提出的原子结构的核式模型，下列说法中正确的是（　　）

禁烟中的一次重大事件是什么？

如图，在四面体A﹣BCD中，AD⊥平面BCD，BC⊥CD，CD=2，AD=4．M是AD的中点，P是BM的中点，点Q在线段AC上，且AQ=3QC．

（1）证明：PQ∥平面BCD；

（2）若异面直线PQ与CD所成的角为45°，二面角C﹣BM﹣D的大小为θ，求cosθ的值．