如图所示，质量相同的两小球a、b分别从斜面顶端A和斜面中点B沿水平方向抛出后，恰好都落在斜面底端，不计空气阻力，下列说法正确的是（   ）

    My name is Jim. My favorite day is October 18th, because it's my birthday. I am very happy on that day. I eat eggs for breakfast. Then my friends come to my home and play with me. We sing and dance. Someone plays the piano and someone plays the guitar. Lunch is very nice. After lunch, my parents take me to see a movie. My favorite movies are action movies(动作片). After supper, my parents, my sister and I watch TV. Then I go to bed at ten thirty. I don't do my homework on that day. I am very tired but happy on my birthday.

例：如果我是阳光，我将照亮所有的黑暗。
                           ，                                
                           ，                                

从“征服意大利半岛”“布匿战争”“称霸地中海地区”“凯撤夺取政权”这些关键词中提炼出的学习主题是（  ）

∠BAC=40°，∠1=∠2，则下列结论：

①CB⊥CF；②∠1=70°；③∠ACE=2∠4；④∠3=2∠4，

其中正确的是（   ）