1. 此合同無效。
   This contract is null and void.
2. 他不根據前提推理因而論證無效。
   This non sequitur invalidates his argument.
3. 他的所有權是無效的。
   His claim to ownership is invalid.
4. 護照過期是無效的。
   A passport that is out of date is invalid.
5. 我試圖說服他，但無效。
   I sought to persuade him, but in vain.
6. 這張支票已經蓋章無效了。
   The check was marked void.
7. 他父親的一切勸告都無效。
   All his father's exhortations were in vain.
8. 這藥無效。
   This medicine is of no avail.

無的英語翻譯：

效的英語翻譯：