( )21. — I’m dead tired. I can’t walk any farther, Jenny.
— _______, Tommy. You can do it!
A. No problem B. No hurry C. Come on D. That’s OK
( )22. Students are encouraged to _________ the design competition for robots at the university.
A. take part B. operate C. join to D. participate in
( )23.I’ll do whatever I can ____ my English.
A. improve B. to improve C. improving D. to improving
