21. A contract may be modified if the parties reach a consensus through consultation.
    當事人協商一致即可以變更合同。
    22. Any amendments to this contract shall become effective only by a written agreement by Party A and Party B.
    對本合同的任何修改，只有經甲、乙雙方簽署書面協議后方能生效。
    23. Any annex is the integral part of this contract.
    本合同一切附件均為本合同的有效組成部分。
    24. Any departure from the terms and conditions of the contract must be advised in writing.
    任何與合同條款相背離的地方，都應以書面形式通知。
    25. Any failure by a party to carry out all or part of his obligations under the contract shall be considered as a substantial breach.
    一方當事人不履行本合同的全部或任何部分義務均應被視為是根本違約。