Although he has failed many times, he keeps _____ hard to make his dream come true.A. working B. to work C. worked
------How often ______ she exercise? ------Twice a week.
Which do you like _______, English or Chinese?
The book is_______. I feel_____.
---Who teaches______singing? ---Nobody, I learn it by_______.
There is____with my computer. Can you help me mend(修理) it?