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简单机械教学资源包中小学科学教学演示教具
54*48 * 18C(54*48*18C) | ¥0.0 | 999 piece available |
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斜面;1.引課。當我們往貨車上裝貨,往往搭一塊木板,把重物搭一塊木板推上車。問題:為什麼要搭這塊木板呢?預設答案:省力。......
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