1 . Donna was ________ ________ ________ (领先) at first in the race, but after the second round, she fell behind the other girls. (根据汉语提示完成句子）

2 . His diet ________ various vegetables, including carrots, tomatoes and potatoes (由……组成). （根据汉语提示完成句子）

3 . Many people don’t know that it may take hundreds of years for a single plastic bottle to ________ in natural environment (分解). （根据汉语提示完成句子）

4 . Taking short showers of less than eight minutes instead of baths is a useful tip on ________ c________ (节约用水). （根据中英文提示填空）

5 . I hope you make a success of your new life in Canada — and don’t forget to k________ (保持联络). （根据中英文提示填空）