If you cannot test geothermal heating principle to the construction, and the ground is absolutely not allowed to drill hammer and hammer nails, to prevent the destruction of the heating coil.

如果无法进行地热加温试验原则上不给施工，而且地上绝对不允许电锤打眼和锤钉，防止破坏加热盘管。

youdao

Put some iron nails at the bottom of a test tube.

把一些铁钉放在试管的底部。

youdao

The deeper the needle penetrated, the more flexible the nail. (The squeamish may wish to note that this test can be done using a fingernail clipping.) In a test of 30 people, Dr Towler found that the nails of those with osteoporosis were significantly softer than those of people without it.

ECONOMIST: Medicine