根本违反合同是指一方当事人因违反合同的结果，如使另一方当事人蒙受损害，以至于实际上剥夺了他根据合同规定有权期待得到的东西，即为根本违反合同。
买方不履行其在合同或本公约中的任何义务，等于根本违反合同时，卖方可以宣告合同无效。
The Buyer may declare the contract avoided if the failure by the seller to perform any of his obligations under the contract or this Convention amounts to a fundamental Breach of contract.
买方只有在完全不交付货物或不按照合同规定交付货物等于根本违反合同时，才可以宣告整个合同无效。
The buyer may declare the contract avoided in its entirety only if the failure to make delivery completely or in conformity with the contract amounts to a fundamental breach of the contract.
预期违约如果在履行合同日期之前，明显看出一方当事人将根本违反合同，另一方当事人可以宣告合同无效。
If prior to the date for performance of the contract it is clear that one of the parties will commit a fundamental breach of contract, the other party may declare the contract avoided.
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