短語詞組短語iff if and only if 有而且只有If -and-only-if 定義與“當(dāng)且僅當(dāng)IF -AND-ONLY- gate 若且唯若閘;等同門;翻譯And Only If 且僅當(dāng)if and only if 當(dāng)且僅當(dāng)in and only if 當(dāng)且僅當(dāng) 返回 if and only if