问题
选择题
We mustn't take _____. We'd better play _____. [ ]
A. chance; safe
B. chances; safe
C. a chance; safety
D. a chance; safely
答案
答案:B
We mustn't take _____. We'd better play _____. [ ]
A. chance; safe
B. chances; safe
C. a chance; safety
D. a chance; safely
答案:B
请应用“物质性质决定用途”的规律,完成下表:
物质化学式 | 性 质 | 用 途 | |
例子 | CO2 | 在一定温度下能形成固体 | 制作干冰,用于人工降雨 |
(1) | ______ | 在空气中可燃烧 | 可作为汽车燃料 |
(2) | ______ | ______ | ______ |