---May I use your computer, Alex? ---Sorry. Mine _____.
—Excuse me, Professor Smith, I was wondering if I could leave a quarter earlier today. — _____ .
Green products are becoming more and more popular because they are environmentally _________.
—Are you going there with us? —If Mary wants to go, ______.
---Can you finish the difficult task in such a short time? ---No, it is beyond my __________.
---I’m afraid I don’t have the ability to make a speech in public. I’m too nervous. ---Don’t worry. You will overcome it _______if you practice more.