Han Han's books are popular. They __________ by many teenagers.
H+____; OH﹣____; CO32﹣____; Cl﹣____; SO42﹣____;NH4+____.
已知fx=x+2+x-4的最小值是n,则二项式x-1xn展开式中x2项的系数为( )
亚洲大多数居民属于( )