甲是一种比较清洁的燃料,已知甲和乙能在一定条件下反应生成丙和丁。
如图2所示的电路,合上开关,小灯泡正常发光若将小灯泡和电流表的位置互换,则合上开关后的现象是( )
根据提示,补全对话。
— What colour is your ball?
— It's ____ and ____.
We want students for the school show. If you _________ play the guitar, please talk to Mr. Zhang after school.
如图,BE是圆O的直径,A在EB的延长线上,AP为圆O的切线,P为切点,弦PD垂直于BE于点C.
(1)求证:∠AOD=∠APC;
(2)若OC:CB=1:2,AB=6,求圆O的半径及tan∠APB.