1．The ________ (大气层) of the earth is filled with carbon dioxide, oxygen, nitrogen and other gases.
答案：atmosphere
2．________ (不像) my brother, I'm good at swimming, while he is good at football.
答案：Unlike
3．He forgot to turn on the TV and ________ (因此) missed the program.
答案：thus
4．Children should not be allowed to watch ________ (暴力的) movies.
答案：violent
5．The final cost would be as much as one ________ (十亿) dollars.
答案：billion
6．Windows XP, Windows Vista and Windows 7 are computer s________.
答案：systems
7．It's important for everyone to apply t________ to practice.
答案：theory
8．As we all know, smoking is h________ to people's health.
答案：harmful
9．We can't e________ without food or water.
答案：exist
