close sand

Close the window at once, lest wind and sand should blow in.

快把窗户关好, 不然风沙就会刮进来.

In addition, there was close relation between the physicochemical properties of different soils and the reduction rates of Nitrobenzene compounds, showing the rule of clay light loam sand.

不同土壤物理化学性质与硝基苯类化合物的还原率有密切关系，表现为黏土轻壤土砂土的规律；

The earliest form was a simple bamboo tube packed with sand that was strapped to a spear. Such a weapon would have been able to blind an enemy and give the wielder the advantage in close quarters combat.

它最早的形式是：把装满沙子的竹筒绑在一个长矛上，这样，就可以弄瞎敌人的眼睛，在近距离搏斗中取得优势。

This time's sand, crystal clear, hard, is full, is close.

这时候的沙子，晶莹、坚硬、饱满、紧密。

When the sands movement starts, the concentration very close to the sand surface is changeless with the wind velocity.

风沙运动一旦发生时，靠近沙床表面的沙粒浓度随风速变化很小，可以认为趋于稳定，达到最大值。