Vous avez cherché: if and, only if (Anglais - Chinois (simplifié))

if and only if
当且仅当

only if
只要不是

once and only
唯一一次

the one and only
别无分号

the one and only way
不二法门

5.2 an intangible asset should be recognized if, and only if:
5.2 在并且只在下列情形下，才应该认列无形资产：

only if oneself do not do
除非己莫为

“(4) the presumptions in paragraph (3) shall apply if, and only if
"(4) 在下述情形下而且只有在下述情形下，应适用第(3)款中的推定：

(only if significant to economy)
对外贸易 - 服务(仅当对经济比较重要时)

advances can be achieved if, and only if, direct dialogue and effective mediation are employed.
如果，而且只有进行直接对话和有效力的调停，才有可能取得进展。

(output indicators only if available).
（产出指标，如果有的话）。

11.9 an enterprise should offset current tax assets and current tax liabilities if, and only if, the enterprise:
11.9 企业冲消流动税款资产和流动税款负债的条件，而且是唯一条件如下；

but this will be possible if, and only if, the parties to the conflict live up to their responsibilities to enable and facilitate access.
但是，只有冲突各方履行其允许并便利进入的责任，这才是可能的，除此之外绝无可能。

only nondangerous recyclable waste may be exported, and only if the exporter has obtained the proper licence.
出口者只有在获得适当许可后才可出口可以回收的非危险废物。

i am confident that we will prevail on that journey, but only if we are not complacent or passive and only if we support and defend our deeply held values.
我相信，我们定会在这一征程中占据上风，但是唯一的条件是，我们不固步自封或采取消极态度，同时，我们支持和捍卫我们根深蒂固的价值观。

and only if a treaty is drafted against this background will it enjoy wide support and be properly implemented.
因此，只有在这种背景下拟定的条约，才能取得广泛的支持并得到妥善执行。

it has been argued that this could be the case if -- and only if -- those targeted have a nexus to the same organized armed group.
有人认为，上述说法成立的条件 -- -- 而且是唯一的条件 -- -- 是成为攻击目标的人与相同的有组织武装团体保持联系。

(3) to be completed for movements within the oecd area and only if b(ii) applies.
(3) 如果b(ii)项在此适用，应针对经合组织所属地区内的越境转移予以填写。

at this rate, the goal will be attained by 2215, two hundred years after what was envisaged, and only if our species survives the destruction of its environment.
按照这一速度，上述目标要到2215年才能实现，也就是比原先设想的时间晚200年，而且条件是如果我们人类还能够在环境遭到破坏后存活下来。

2. at h duty stations, mobility is paid upon fourth assignment and only if staff member had at least two previous assignments at a to e duty stations
2. 在h类工作地点，第四次派任、并且以前至少两次派到a类至e类工作地点的工作人员可得到调动津贴