adsl在实际应用中存在选线率问题。_爱下问搜题

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问题判断题

adsl在实际应用中存在选线率问题。

答案

参考答案：对

填空题

用方框内所给词的适当形式填空。

learn, have, write, start, call

1. I _____ to ride a bike when I was four years old.
2. Students usually _____ learning English in primary schools.
3. They _____ a big party to celebrate (庆祝) the harvest last October.
4. Professor Li stopped _____ after he had a heart disease.
5. I _____ Lucy last night, but she was not at home.

填空题

光电二极管的PN结工作在反偏状态，它的反向电流会随光照强度的增加而（）。