题目

China is the only nuclear state ________ not to be the first to use nuclear weapons or to use nuclear weapons against non－nuclear weapon states. A．undertaking  B．to undertake C．having undertaken  D．undertaken 答案：B　[句意：中国是唯一的核国家承诺不首先使用核武器，不对无核国家使用核武器。当名词被序数词或only等词修饰时，其后用不定式作定语。]

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