如何设计一个定时器可以定时20秒30秒40秒50秒60秒接通蜂鸣器请给出最简单的电路图谢谢
2025-02-06 10:39:17 2025-02-06 10:39:17 2025-02-06 10:39:17 2025-02-06 10:39:17 2025-02-06 10:39:17 2025-02-06 10:39:17 2025-02-06 10:39:17 2025-02-06 10:39:17 2025-02-06 10:39:17 2025-02-06 10:39:17 2025-02-06 10:39:17 2025-02-06 10:39:17 2025-02-06 10:39:17从云南带回来的干花装箱时被捆扎的很紧回家后如何让它们自然散开呢
2025-02-06 10:39:17 2025-02-06 10:39:17我用pvc管引用河水到田里管径110的距离有一公里开始200米有一米的落差
2025-02-06 10:39:17 2025-02-06 10:39:17 2025-02-06 10:39:17 2025-02-06 10:39:17 2025-02-06 10:39:17 2025-02-06 10:39:17 2025-02-06 10:39:17 2025-02-06 10:39:17 2025-02-06 10:39:17 2025-02-06 10:39:17 2025-02-06 10:39:17 2025-02-06 10:39:17 2025-02-06 10:39:17 2025-02-06 10:39:17