2个很难解释的英语句子----务必高手帮忙
In 1921,aged 27,Mao helped start the Chinese Communist Party.
Two years later,he became a member of the Party’s leading group.After 1949,when he founded the People’s Republic of China,Mao did much to free the country from hardships（艰难）.During the 1960s he made some mistakes,such as the “Cultural Revolution”,but he still did much good for his time.
【解释1】Mao helped start the Chinese Communist Party.中,start 如何翻译?
【解释2】but he still did much good for his time.中,did much good不太明白,还有for his time 如何翻译也不太明白.