井下一氧化碳的最高允许浓度可以超过0.0024%。()
参考答案:错
Workers were celebrating after the world's longest water diversion tunnel(引水隧道)
was _____in northeast China's Liaoning Province, on April 15 ,2009. [ ]
A. competed
B. completed
C. compared
D. companied
制备阿胶时加入冰糖的目的是
A.增加稠度
B.沉淀胶液中的泥土杂质
C.增加胶剂的透明度
D.降低黏性,便于切制
E.增加黏性,易于成型