青云翻译

Then fill in the cracks of gravel, and finally the screen and the casing annulus packed gravel.

Then fill in the cracks of gravel, and finally the screen and the casing annulus packed gravel.

Then fills up the broken stone in the crack, finally again in sieve tube and set of pipe ring spatial backfill broken stone.

And then the cracks filled with gravel and then finally in the sieve tubes and casing ring air-filled with gravel.

Then fill in the cracks of gravel, and finally the screen and the casing annulus packed gravel.