A:他好不容易找到了一份安定的工作,希望从此可以结束颠沛流离的生活。
B:从现在开始这样做并以身作则,这将会培养孩子的同情心。
C:遇到不懂的问题,同学们总喜欢向老师请教,这种不耻下问的精神值得提倡。
D:对于外界关心的传言,他只是付之一笑,避而不答。
Tai Lihua is a Chinese woman. She is very beautiful. As a child, she became deaf and dumb(哑的). She couldn't hear or say. She was very sad. Later, she had a teacher. The teacher taught her to dance. Though she couldn't hear, she was very hardworking. She danced very well. Now, she is very famous. She is not sad any more.
在Rt△ABC中,∠C=90°,sinB= 22 ,则∠A的度数为( )
如图,已知AB⊥平面ACD,DE⊥平面ACD,三角形ACD是正三角形,且AD=DE=2AB,F是CD的中点.
(1)求证:平面CBE⊥平面CDE;
(2)求二面角C﹣BE﹣F的余弦值.
媒体报道:染发剂常用到的着色剂﹣对苯二胺,化学式为C6H8N2.是一种有毒的化学品,有致癌性.计算(不要求写计算过程):