如图,平面上有两个全等的正八边形,∠BAC为( )
A:60°
B:45°
C:30°
D:72°
Today is Monday. Linda is at school. She has Chinese,English and PE in the morning. She doesn't have Music today. She has Maths and Art in the afternoon. She has Music on Fridays.
已知数列 的各项均为正整数,对于任意n∈N*,都有 成立,且 .
1972年8月7日,太阳表面突然出现增大、增亮的斑块,使强烈的X射线、紫外线和射电波伴随着大量带电粒子流,连续猛烈轰击地球达一星期之久。在爆发开始后5小时之内,有一股粗16千米,长达7万多千米的带电粒子流,以6500千米/秒的高速闯进地球大气层。顿时,地球上几乎所有飞机和轮船上的磁盘指针都动起来,全世界的电报通信彻底中断,极地上空出现美丽的光带。下列关于太阳活动对地球影响的叙述中正确的是
— No, I ________ go to the cinema. The tickets are too expensive.