A. only occurs at night and early morning B. is most likely with Polar Maritime air C. will only clear by insolation D. can sometimes last for 24 hours or more in winter
A. a meteorological report B. an ice report C. the first weather forecast D. an important message that cant be rejected
A. 火焰较短，高向不均匀，水分含量大，不易净化管件易堵 B. 火焰较短，高向加热欠佳，煤气含尘量大，需要预热，易堵格子砖
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