Celestite is usually diagenetic but commonly forms very early in the history of the sediment.天青石一般是成岩期的,但通常是在沉积史的极早期形成的.Reduction - metathesis method for preparation of strontium carbonate from celestite is developed.提出还...
投石机: 古代投掷物体之发射器,用作发射长箭或重型球状物.Ballista: Ancient missile launcher designed to hurl long arrows or heavy Balls.最大之投石机可相当准确地发射27公斤重物到约450 公尺 处的目标.The largest could accurately hurl 60 - lb ( 27 - kg ) weights up to about 500 ...
Some people say smoking calms your nerves.有人说，吸烟可以放松神经。Heavy rains are followed by clear sky, strong winds by light winds or calms.大雨过后,天空晴朗; 狂风以后,微风或静寂.The human protein, on the other hand, calms the immune system down....