This Paper presents the features of ash haydite, producting process, commercialized, economic benefits and so on.本文介绍了免烧粉煤灰陶粒的特点 、 生产过程 、 商品化以及经济效益等....
Daniel arrived in Maryland as an indentured servant.丹尼尔作为契约佣工来到马里兰州。They are descendants of indentured importees.他们是契约外来工的后代.His son was indentured to the local blacksmith.他的儿子拜当地的铁匠为师签订了师徒合同....