| 1 | "You can't hire a rig in Texas now, " said Phil, "they're too much in demand. | |
| 2 | In course of sinking the well-shaft they came upon a deposit of a very rare mineral. | |
| 3 | The security of freezing wall is the key problem of freezing shaft sinking in deep alluvium. | |
| 4 | This paper analyses the piston effect problem in dellling shaft sinking method and its detriments. | |
| 5 | There were two main sources of water supply for a city in the Pre-Qin period, one was drilling wells for water, the other was digging ditches to draw water. |
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