He noticed the helicopter hovering over the field. Then to his astonishment, he saw a rope ladder _____ out and three men climbing down it.
A. throwing
B. being thrown
C. having thrown
D. having been thrown
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_____ regular training in nursing, she could hardly cope with the work at first.
A. Not received
B. Since receiving
C. Having received
D. Not having received
Arriving at the bus stop, _____ waiting there.
A. a lot of people were
B. he found a lot of people
C. a lot of people
D. people were found
一根重2600Kg规格为Φ600mm长2000mm的TC11的自耗电极,要化成Φ700mm的成品铸锭,铸锭补缩需要消耗自耗电极195Kg;,按工艺规定熔化结束跳闸时自耗电极剩余厚度为20mm。试计算开始补缩时行程为多少?
电子束冷炉床熔炼法具有传统熔炼法不具备的优异功能,请简答电子束冷炉床与传统熔炼法相比有哪些优异功能?