在三包有效期内，家用视听商品消费者理论上可以凭哪些材料要求销售者、修理者、生产者负责修理、更换。销售者、修理者、生产者应当按照《家用视听商品修理更换退货责任规定》负责修理、更换（） ["商品条码","发货票","三包凭证","三包有效期证明"]
变压器室的外窗要求为（）。
No sooner （） than they started to repair the sludge pump. ["the second engineer had got into the engine room","the second engineer got into the engine room","has the second engineer got into the engine room","did the second engineer get into the engine room"]
高校学生学习应遵循哪些原则？
烧结生产对布料有哪些技术要求？
从病理学理论上看，防治植物病害有哪些方法？
