______ trees were cut down. And many birds lost their home.
A. Two thousandsB. Thousands of D. Thousand of
I spent a lot of time ______ English last weekend.
A. to practice speaking B. practicing to speak C. practicing speaking
We didn't go home ______ the old man was sent to the hospital.
A. until B. when C. while
—Could I borrow your computer. Bob?
—Sorry, I am______ it.
A. taking out B. turning on C. working on
Dear students, please read every sentence carefully. The more _____ you are, the______ mistakes you'll make.
A. carefully; fewer B. careful; less C. careful; fewer