It’s more than half a century ________ my grandfather joined the Party and became a servant to the people.

      is no doubt that the Great Wall is one of the wonders of the world.

Many students in this school make __________ a rule to come to the evening classes even on Saturdays and Sundays.

Zhang Yining has trained continuously for six hours. ______ she is tired out. 

    ，please start the work tomorrow.