Ⅰ.单句语法填空
1．The door has been locked (lock) so no one of us can enter the room now.
2．They have been told (tell)about it for many times，but in vain.
3．He has been asked(ask)about his life on the lonely island for many times.
4．Within the last 70 years，China has been changed (change )beyond recognition.
5．The living conditions of my hometown has been improved (improve) a lot，for instance，almost every family has one or two cars.
6．How long has the machine been used (use) ? We need this essential information of it.
7．3Dprinting technology has been put (put) into production to make replacement hearts and bone parts.
