A:①②
B:③④
C:①④
D:②③
求出下面一组数的最大公因数和最小公倍数.
23和92____
如图,正方形ABCD内接于⊙O,E为DC的中点,直线BE交⊙O于点F,若⊙O的半径为2,则BF的长为____ .
We can't hear clearly. Can you speak as ____ (loudly) as possible.
《西游记》中“唐僧”的人物原型是( )
单项式-2πx3y2z的系数和次数分别是( )