我国是____ 领导的、以____ 为基础的____ 的社会主义国家。
如图,圆O是三角形ABC的内切圆,求证:AB+CF=AC+BF.
下列四组词语中不全是贬义词的一组是( )
Modern medicine ____ (develop) so quickly recently that many diseases can he cured.