为什么可以说libraries are a good place to study?

100词写作社群里面出现了一个句子：

Thirdly, as their lives are being dominated by smartphones, students and workers are susceptible to nomophobia, feeling extremely anxious about not having access to their phones. This means they are becoming a slave to their phone.

有同学问到了这样一个问题：

为什么they后面可以跟一个单数名词a slave? 是不是要改为slaves?

这是一个挺有代表性的问题，they are becoming a slave这种说法是对的。它属于地道英文里面经常出现的一个结构：XX are a place/student/person… 比如《纽约时报》就有这样一个句子：

Libraries are more relevant than ever. They are a place for personal growth and reinvention, a place for help in navigating the information age, a gathering place for civic and cultural engagement and a trusted place for preserving culture.

回到前面的句子，they are becoming a slave to their phone这里"a slave"不能理解为“一名奴隶”，而是一个泛指的概念，相当于slaves，句子实际上相当于：they are becoming slaves to their phone

《卫报》里面也有两个类似的例子：

(1) Will that make me more popular, or more successful? People are a slave to winning other’s approvals.

(2) We are slaves to the printed word, but only handwriting conveys real beauty

在英语主系表结构中，主语和表语的数可以出现不一致的情况。实际上，英语中不仅存在XX are a place/student/person…这种结构，还有A problem is XX（XX为名词复数形式）这样的用法。比如《牛津英语用法指南》中出现了一个句子：A serious problem is wasps.

书中提到，在英语SVC结构中，动词通常与句子的主语保持一致，而不是与后面的补语保持一致。比如The biggest timewaster is meetings. 其中谓语动词is与the biggest timewaster保持一致，而不与meetings保持一致。

《牛津英语用法指南》还提到，如果主语与动词相隔很远，有时候会将动词与补语保持一致。比如这个句子：

The most interesting thing on radio and television last weekend, without any doubt, was/were the tennis championships. 

句子中主语为the most interesting thing，但因为和动词隔得太远，因此动词可以和补语the tennis championships保持一致。

如果主语是what引导的关系从句，并且补语又长，也常常会出现这种情况，比如：

What I am most interested in is/are your immediate personal reactions. 

平时遇到类似的句子可以多加留意。

我们最近推出了新概念英语三写作社群，通过对新概念三课文中经典句型的训练来提升遣词造句能力。社群明天开班，有需要的同学欢迎参加：如何通过仿写新概念英语三提升写作水平？