为限: be within the limit of; not exceed; be good for ... only 短语和例子有效期以一个月为限 be effective within the limit of a month; be good for one month only; 载重以五吨为限。 the load should be no more than five
有效期: term of validity; period of validity 短语和例子延长合同的有效期 prolong the contract's period of validity; 这个胶卷已过了有效期。 this film has passed its expiry date