There must, therefore, be a third force.

因此，肯定有第三股力量存在。

youdao

And the third force, humanistic psychology came as a reaction to it.

第三势力，人本主义心理学作为对其的异议出现。

哈佛公开课 - 幸福课课程节选

Later in September, the Amsterdam, Brussels and Paris bourses finalised their union, to create Euronext, a third force in Europe.

ECONOMIST: Deutsche B?rse

Despite the emergence of the centrist contender Francois Bayrou as a third force at the presidential election, the parliamentary vote largely confirmed the two-party system.

BBC: NEWS | Europe | Sarkozy's ambition remains intact

Some voters hedged their bets in the proportional-representation part of the ballot by supporting the new Your Party that is fast emerging as a third force in Japanese politics (see article).

ECONOMIST: Japan's upper-house elections