支线放大器的作用是什么？
参考答案：
用来进一步放大支线信号，以供给用户分配网络更高的电平，带动更多的用户。
一质量m=0.5kg的滑块以一定的初速度冲上一倾角θ=37°足够长的斜面，已知滑块上滑过程中的v-t图象如图所示．取sin37°=0.6．cos37°=0.8，g=10m/s2，求：
（1）滑块与斜面间的动摩擦因数；
（2）滑块返回斜面底端时的速度大小．
用所给词的适当形式填空。
1. Which is the ________(far) from Zhengzhou, Beijing, Shanghai or Sonya?
2. Taiwan is in the________ (south) part of China.
3. Which is________ (popular), pop songs or classical songs?
4. People there are________ (friend) to visitors.
5. He left the town without________ (say) goodbye to anyone.
6. Spring is the most ________ (love) season of a year.
7. The price of this computer is the________ (high) of the three.
8. Bill Gates won a great________ (successful).
9. It's not easy_________(learn) English well.
10. My sister wants to be a________ (act) when she grows up.
