问题
选择题
| 下列说法中正确的是（ ） A．X射线穿透物质的本领比γ射线更强 B．红光由空气进入水中，波长变长、颜色不变 C．狭义相对论认为物体的质量与其运动状态有关 D．观察者相对于频率一定的声源运动时，接受到声波的频率一定保持不变 |
答案
答案：C
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| 下列说法中正确的是（ ） A．X射线穿透物质的本领比γ射线更强 B．红光由空气进入水中，波长变长、颜色不变 C．狭义相对论认为物体的质量与其运动状态有关 D．观察者相对于频率一定的声源运动时，接受到声波的频率一定保持不变 |
答案：C
| 阅读理解。 | ||
A.Yes, it's very nice. B. No, but we can breathe it. C. Yes, it has taste. D. No, but we can smell it. 2. What does the underlined word "They" refer to ( 指的是)? A. Wind and air. B. Smell and taste. C. A kite and a plane. D. Wind and clouds. 3. A balloon can lift people up with _________. A. hot air B. soft wind C. smell D. taste 4. What does the poem mainly (主要地) try to tell us? A. We need air sometimes. B. It's hard to stay in the air. C. Air is too little to waste. D. Air is very important to us. |
