Atmosphere laden with coal dust or grain dust caused by loading these cargoes（）.
煤成气（coal derived gas)是天然气。A正确B错误
煤层(coal bed)是？
3、Damage to cargo caused by dust is know
Damage to cargo caused by dust is known as（）.AcontaminationBoxidationCtaintingDvaporizatio
4、Atmospheres laden with coal dust or gr
Atmospheres laden with coal dust or grain dust caused by loading these cargoes（）.Arequire loading operations to be shut down until the atmosph...
5、The atmosphere（）certain gases mixed to
The atmosphere（）certain gases mixed together in definite proportions.Acomposes ofBis made upCconsists ofDmakesup of
6、The vowel is produced without (or with
The vowel is produced without (or with little) restriction during its production and is always voiced.（）A正确B错误