I ________this book for about a month, so I have to return it as soon as possible.
By the time I locked the door, I realized I ________ my keys at home.
It is cruel___ them to catch the sharks and cut______ their fins.
- Would you please take this workbook to the teacher's office for me? — ________.
I regret ______ to my head teacher,not listening to him.
—The meeting _______ because of the fog in Northern China last week. — Oh, it’s too bad! We should take action to improve the air quality.