He joined the army __________2000.
Lily and her sister look the same. I can't tell one from_______.
Sam likes trekking_______the jungle, because he thinks it's exciting.
_______15th International Film Festival will be held in Shanghai.
—I'm doing a survey. Could you tell me ______?—Sure. I usually go to work at 7:00 am.
—How often do the students play sports?