以.为基准用英语怎么翻译?要求语法准确,并举例说明,

Based on 捐赠必须以实际需求为基准。Donations must be based on an actual demand。固定参考价格应以1986至1988年为基准期,一般应为用于确定支付率的实际价格。The fixed reference price shall be based on the years 1986 to 1988 and shall generally be the actual price used for determinining payment rates