a works is/are

一般都把作“工厂”解的 works 看作单数。因此，谓语动词应当使用单数。

1. An enormous works was built here in the thirties. 三十年代这里建造了一家巨大的工厂。

2. The steel works is closed for the holidays. 这家钢厂在假期不开工。

但是，也有人在这种情况下，使用复数动词：

1. The steel-works were closed for the Christmas holidays. (ALD) 这家钢厂在圣诞节期间不上班。

2. The works have been closed since January. 这家工厂自一月份起就关闭了。

CEED 明确指出, a works 可用单数动词或复数动词:

The works are closing this autumn. 这家工厂将在今年秋天关闭。

由此看来，上面的试题不够恰当。今后应避免出类似试题。