Noisy as it was, he went on reading as if nothing ______ .

为何答案是were happening而不是had happened?

这两个不都是虚拟语气吗?


是的,填 were happening 和 had happened 都是虚拟语气,但使用方法不同:用 were happening 表示当时正在发生的状况,用 had happened 表示针对当时来讲属已经发生的状况。对于你的句子来讲,非常显然 were happening 更符合句子语境,指“吵闹”的状况当时“正在发生”。句意:

Noisy as it was, he went on reading as if nothing were happening. 虽然非常吵,但他仍继续看书,仿佛啥事都没发生一样。(指当时本来非常“吵闹”,但对他来讲,仿佛当时“吵闹”的事没正在发生)