Complex sentence: Hellman was praised for sacrificing her career by refusing to answer questions by HUAC; but her denial that she had ever belonged to the Communist Party was easily disproved, and her veracity was doubted by many, including war correspondent Martha Gellhorn and literary critic Mary McCarthy.
Split into simpler sentences: Hellman was praised for sacrificing her career by refusing to answer questions by HUAC. But her denial that she had ever belonged to the Communist Party was easily disproved, and her veracity was doubted by many, including war correspondent Martha Gellhorn and literary critic Mary McCarthy.