______ better in 2010 World Expo is the duty of every citizen in Shanghai.
| A．Being served | B．Serving | C．Serve | D．Having served |
Please do me a favor—________ my friend Mr.Smith to Youth Theater at 7：30 tonight.
| A．to invite | B．inviting |
| C．invite | D．invited |
Nowadays people sometimes separate their waste to make it easier for it ________.
| A．reusing | B．reused |
| C．reuses | D．to be reused |
At the age of 29，Dave was a worker，________ in a small apartment near Boston and ________ what to do about his future.
| A．living；wondering | B．lived；wondering |
| C．lived；wondered | D．living；wondered |
When he ________ the door，he found his keys were nowhere.
| A．would open | B．opened |
| C．had opened | D．was to open |
In April,2009，President Hu inspected the warships in Qingdao，________ the 60th anniversary of the founding of the PLA Navy.
| A．marking | B．marked |
| C．having marked | D．being marked |