Sorry, I can’t work out this problem. —Try again, please. It’s only ______ difficult.
My bike is missing. I can’t find it anywhere.– I’m afraid you have to buy .
Is this __________book?–No．That is ___________ book．
Why don’t you take some exercise? Sitting before the computer is bad for your health. —________, but I have to finish my work on time.
Tommy，can you ________ these words with the pictures?一Sorry，I can’t．