Very slow - grown softwoods have excellent workability.生长非常慢的针叶材有着特别好的加工性能.There are two main kinds of timber trees - softwoods and hardwoods.用材树种有两大类 -- 软木材与硬木材....
希腊生产耐火级铬铁矿石已有百余年历史.Greece has been producing refractory grade chromite ore for more than a hundred years.许多由沙漠侵入这些牧场的灌木种都是耐火的.Many of the desert scrub species that have invaded these ranges are fire intolerant.硅酸铝 ( 陶瓷 )...