indate
useful life
expiry date
effect duration
term of validity
effective period
period of validity
参考例句：
Expiry Date证书有效期
The embassy refused to renew their temporary travel documents.大使馆不同意延长他们临时旅行证件的.有效期。
Review the expiry date (use them within a year or two of the date they were manufactured).检查有效期限（生产后一至两年内为有效期）。
The ticket is available for three days.这张票有效期三天。
They applied for an extension to their visas.他们申请延长签证有效期。
Initially the contract will be in effect for 3 years.最初契约的有效期为三年。
He asked for an extension of his visa.他申请延长签证有效期。
The LC is only valid until April the eighth.信用证的有效期只到四月八号。
The validity of the L/C will be extended to 30th August.信用证的有效期将延至8月30日。
This membership fee lasts for 12 months and is non-refundable.这会员费有效期12个月中途不退款。
indate是什么意思：
有效期
useful是什么意思：
adj. 有用的，有益的
It is used as a reflexive.它被作为反身代词使用。
That was a balk to us.那对我们是个挫折。
They help us to be maximal encouraging to us.他们来帮助我们对我们是个极大的鼓舞。
