1 . They were so frightened that they had the fire________ (burn) all night. (所给词的适当形式填空)

2 . My sister bought this T-shirt at such a low price. She was really good at ________ (讨价还价). (根据汉语提示单词拼写)

5 . The campsite provided only_________ (base) facilities. (所给词的适当形式填空)

6 . The guide gives a ________(简洁的) talk on the history of the smartphone.(根据汉语提示单词拼写)

7 . One of the greatest________ (benefit) of the Internet was its ability to remove the distance that usually exists between people. (所给词的适当形式填空)

8 . I like getting up early in the morning. You know the morning air is so good to__________(breath). （所给词的适当形式填空）

9 . We should try to keep the ________(平衡) of nature to protect the earth.

10 . _______ (bite) twice, the postman refused to deliver our letters unless we chained our dog.