51．2如無工程師的書面命令，承包人不得作任何此種變更。然而，如工程量的增減不屬本條規定的應作命令的範疇，而是因超過或不足建築工程清單的規定所至，則不要求有書面命令。另外，如工程師因任何原因認為有必要口頭作此種命令，承包人必須服從，且工程師對該口頭命令的確認書，不論在命令執行前或後給予，都應被視作是本條款所指的書面命令。此外，如承包人在_______天內書面向工程師要求確認，而工程師在_______天內未用書面駁回此確認，其應被視為是工程師所作的書面命令。
52．（1）all extra or additional work done or work omitted by order of the engineer shall be valued at the rates and prices set out in the contract if，in the opinion of the engineer，the same shall be applicable．if the contract does not contain any rates or prices applicable to the extra or additional work，then suitable rates or prices shall be agreed upon between the engineer and the contractor．in the event of disagreement the engineer shall fix such rates or prices as shall，in his opinion，be reasonable and proper．
52．1凡由工程師命令增減的工程，如工程師認為可行，均應按契約價格予以估價。如契約所列的價格不適用所增減的工程，應由工程師和承包人協商出合適的價格。如不能就此達成協定，應由工程師決定一個他認為恰當的價格。
（2）provided that if the nature or amount of any omission or addition relative to the nature oramount of the whole of the works or to any part thereof shall be such that，in the opinion of the engineer，the rate or price contained in the contract for any item of the works is，by reason of such omission or addition，rendered unreasonable or inapplicable，then a suitable rate or price shall
be agreed upon between the engineer and the contractor．in the event of disagreement the engineer shall fix such other rate or price as shall，in his opinion，be reasonable and proper having regard to the circumstances、
52．2如工程師認為，涉及整個工程或部分工程的質或量的增減，使得本契約中所列的任何工程項目的價格因此種增減而不再合理或不切實際，工程師和承包人則應協商一個合適的價格。如不能就此達成協定，應由工程師決定一個他認為恰當的價格。
provided also that no increase or decrease under sub-clause（1）of this clause or variation of rate or price under sub-clause（2）of this clause shall be made unless，as soon after the date of the order as is practicable and，in the case of extra or additional work，before the commencement of the work or as soon thereafter as is practicable，notice shall have been given in writing：