【单选题】Although he kept trying and failing, I always the belief that he would succeed one day.
【单选题】He started to learn English in 1990 and in the years ________ he kept on using it in his work.
【判断题】美国作家乔叟创作了《坎特伯雷故事集》。()
【判断题】乔叟写过一本名叫《坎特伯雷故事集》的作品。()
【单选题】一个C类网络的子网掩码为255.255.252.252,则该C类网络的主机数目是( )。