B2 based on truth or reason; able to be accepted确凿的；合理的；有根据的；让人信服的
B2 A ticket or other document is valid if it is based on or used according to a set of official conditions that often include a time limit（票或其他文件）有效的，正式认可的
having legal force有法律效力的，有法律约束力的
The judge remarked that ignorance was not a valid defence.
For the experiment to be valid, it is essential to record the data accurately.
Their arguments were valid a hundred years ago and they still hold good today.
You need to trawl through a lot of data to get results that are valid.
The voucher is valid between July and December and entitles you to 10% off all overseas flights.