20．1從開工至按本契約第48條中的竣工證書規定的日期為止，承包人都得對工程全權負責。只要工程師就永久性工程的任何部分簽發了竣工證書，承包人從部分竣工證書中規定的日期起不再對永久性工程的此部分負責，此部分的責任則轉至業主。此外，承包人必須對任何尚未完工而他得在維護期內完成的工程負全權維護，直至此種工程完工。如工程或其任何部分出現任何損害、損失或毀壞，不論何種原因，除本條第2款規定的除外風險外，承包人均得自費負責修理和修補，以確保永久性工程竣工時處於狀態良好，各方面都合乎契約的要求和工程師的指示。如因除外風險而導致任何損害、損失或毀壞發生，承包人必須應工程師的要求（如果有）以及本契約第65條的規定，如上所述，進行修理和修補，費用由業主承擔。承包人也必須對為完成未竣工程或履行本契約第49或50條規定的義務，在施工過程中對工程造成的任何損害負責。
（2）“the excepted risks' are war，hostilities（whether war be declared or not），invasion act of foreign enemies，rebellion，revolution，insurrection or military or usurped power，civil war，or unless solely restricted to employees of the contractor or of his sub-contractors and arisingfrom the conduct of the works，riot，commotion or disorder，or use or occupation by the employer of any part of the permanent works，or a cause solely due to the engineer's design of the works，or ionizing radiation，or contamination by radio-activity from any nuclear fuel or from any nuclear waste from the combustion of nuclear fuel，radio-active toxic explosive，or other hazardous properties of any explosive，nuclear assembly or nuclear component thereof，pressure waves caused by aircraft or other aerial devices travelling at sonic or supersonic speeds，or any such operation of the forces of nature as an experienced contractor could not foresee，or reasonably -make provision for or insure against all of which are herein collectively referred to as“the excepted risks'．
20．2“除外風險”包括戰爭、敵對狀態（無論是否宣戰）、侵略、外國敵人行為、叛亂、革命、起義或兵變或篡權、內戰、或不是由承包商的雇員、其轉包人單獨製造和不是因工程管理而發生的暴動、騷亂或混亂、或因業主使用或占用任何部分的永久性工程、或純屬工程師工程設計的原因、或因任何核燃料或核燃料燃燒後的廢料以及放射性有毒爆炸物引起的輻射和污染、或任何爆炸物、核裝置或核裝置部件的其他危險特性、以音速、超音速飛行的飛機或其他飛行物的壓力波以及其他任何此種自然力的作用，其不能為有經驗的承包商所預見，也不能合理提供物資或投保與之對抗，所有這一切在本契約中都被稱為“除外風險”。
21．without limiting his obligations and responsibilities under clause 20 hereof，the contractor shall insure in the joint names of the employer and the contractor against all loss or damage from whatever cause arising，other than the excepted risks，for which he is responsible under the terms of the contract and in such manner that the employer and contractor are covered for the period stipulated in clause 20（1）hereof and are also covered during the period of maintenance for loss or damage arising from a cause，occurring prior to the commencement of the period of maintenance，and for any loss or damage occasioned by the contractor in the course of any operations carried out by him for the purpose of complying with his obligations under clauses 49 and 50 hereof；