问题
判断题
脉冲的占空比指的是脉冲宽度与脉冲频率的比值。（
答案
参考答案：错
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脉冲的占空比指的是脉冲宽度与脉冲频率的比值。（
参考答案：错
| 短文填空。根据短文意思，从方框中选择合适的单词填在相应的横线上，使短文恢复完整，每空一词。 | |
a tree there. I always 5____________ it. It grows fast. Tomorrow is 6____________. My mother says she is going to 7____________ a trip with me. It's wonderful. We are going by 8____________ and go 9____________ in the sea. I can eat 10____________, too. It's my favourite food. I can't wait. |