1.The fifth generation computers, with artificial intelligence,_____and perfected now.
        a.developed
        b.have developed
        c.are being developed
        d.will have been developed
        2._______ the earth to be flat, many feared that columbus would fall off the edge of the earth.
        a.Having believed
        b.Believing
        c.Believed
        d.Being believed
        3.If Icorrect someone, I will do it with as much good humor and self-restraint as if I were the one____.
        a.to correct
        b.correcting
        c.having corrected
        d.being corrected
        1.The traditional approach_______with complex problems is to break them down into smaller,more easily managed problems.
        a.to dealing
        b.in dealing
        c.dealing
        d.to deal
        2.The ancient Egyptians are supposed_______rockets to the moon.
        a.to send
        b.to be sending
        c.to have sent
        d.to have been sending
        3.Until then , his family_______from him for six months.
        a.didn’t hear
        b.hasn’t been hearing
        c.hasn’t heard
        d.hadn’t heard
        
        1.c
        句尾的now是时态的标志，computer是被发展所以用被动语态。
        2.b
        believe和fall没有时间上的先后，所以不用完成时。
        3.d
        correct的逻辑宾语应该是the one所以应该用被动。
        
        1.a
        approach后接名词和动名词，approach to doing sth.
        2.c
        be supposed to 应该，被期望，表示对过去发生的事情的判断，用完成时.
        3.d
        until then 是时态的标志，until要用完成时，then可以看出主句的行为发生在前，应该用过去完成时。