抗日战争是1937年爆发的。

[误] The Anti-Japanese War was broken out in 1937.

[正] The Aunti-Japanese War broke out in 1937.

注：break out(战争等的爆发)是不及物动词短语，不能用于被动语态。类似的还有 happen, belong,disappear, fail, take place 等。

参考例句：The forecast that war would break out proved true. 战争会爆发的预测被证实了