1．我每周锻炼三次。         I exercise _______ _______ every week．

2．假期你打算做什么。     What are you doing _______ _______?

3．我经常步行，但有时乘公共汽车。     I usually walk but sometimes I _______ a _______．

4．非常感谢你的邀请。                   _______ very much for your _______．

5．我们的教室比他们的干净。        _______ classroom is _______ than theirs．