unimpeachable       
adjective  formal approving uk/ˌʌn.ɪmˈpiː.tʃə.bəl/ us/ˌʌn.ɪmˈpiː.tʃə.bəl/
 (品格)无可怀疑的,无可指责的,无可挑剔的
of such a high standard of honesty and moral goodness that it cannot be doubted or criticized
  A spokesman said the Bishop was a man of unimpeachable integrity and character. 一位发言人说主教是一个正直无私、品格高尚的人。 
 Synonyms: blamelessirreproachable unexceptionable