Then we laid down sheets with electric pads on top of them, then another sheet on top of that, then the sand on top of the that, so the sand covered an area of about three feet.
我们在床单上垫了一层电热垫，再垫上一层床单，最后把沙子辅在最上层，这样沙子总共覆盖了大约3英尺。
In loess hilly gully region covered by sheet sand, soil water erosion process is different from typical loess hilly gully region because of worse natural environment and loose land surface material.
在片沙覆盖的黄土丘陵区，由于恶劣的自然环境及松散的地表组成物质，土壤的水蚀过程明显地不同于典型的黄土丘陵区。
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