试述教师在游戏的现场指导中如何把握好与儿童的互动节奏？
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In the event of a flame failure in an auxiliary water-tube boiler, you must（）
A. relight the boiler immediately to prevent loss of steam pressure
B. relight the fire off the brickwork as the bricks are cherry red
C. purge the furnace of any combustible gases before attempting to relight the fire
D. speed up the feed pump to prevent dry firing when the burner flame is reestablished
看见美国老人上楼或爬山时，要上前去搀扶，这是友好的表现。
A. 正确
B. 错误
造成环境污染和破坏的原因虽然很多、很复杂，（）则是主要原因。
A. 设备
B. 人员
C. 资金
D. 任意排放工业“三废&rdquo
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