分类：教育/科学-升学入学-高考
问题：谢先Manypeoplewatchedtheboys______ 
Many ople watched the boys ______ the mountain at that time. 　　A．climb 　B．climbing 　C．to climb 　D．climbed ???????????
回答：B,因为有at that time.这是这道题的关键.要不就选A