21. Donny helped us get the tickets. We __________to Guangzhou next Wednesday.
A. flew B. fly C. are flying D. will have flown
22. My sister will get up early tomorrow morning，because the train to London _________at 6:00 a. m.
A. will leave B. is going to leave
C. leave D. leaves
23. He ________more than 5,000 English words when he entered the university at the age of l5.
A. had learned B. would have learned
C. learned D. has learned
