Keep in mind, though, for this test work, you must make sure that your diamond is completely clean and free from oil or dirt.

需要牢记的是，在做这个测试时，你必须保证你的钻石是完全干净且没有沾染油污或灰尘。

youdao

The surfaces to be joined must be clean and free from oil, grease and heavy oxides.

连接部位表面必须清洁，没有油污、油脂和氧化物。

youdao

All the surfaces must be free of oil, grease, moisture, dust and other foreign matter before application.

涂装前所有的表面必须没有油脂、水汽和杂质。

youdao

And we must free ourselves from the tyranny of oil.

NPR: Transcript: Obama's Speech at AIPAC

As an affair of the state, Obama must send the signal that the days of free handouts to oil are over.

FORBES: Why POTUS should say no to Keystone