答:Fish and chips 作主语时,谓语动词用单数。
下面是摘自拙作《高考英语能力突破•词汇》上的有关内容:
[语法归纳] 关于主谓一致
1. 由and连接的两个单数名词作主语时,谓语动词用复数,例如:
A poet and a writer have come. 一位诗人和一位作家已经到了。
2. 但是如果and连接的两个部分在意义上指同一个人、事物或概念时,谓语动词用单数,例如:
The teacher and writer is my friend. 这位教师兼作家是我的朋友。
There is a journalist and writer living in America whose name is Alex Haley. 美国有一位记者兼作家,名叫亚历克斯•哈利。
Fish and chips is his favourite. 炸鱼加薯条是他喜欢吃的。(注:fish and chips是一种英国的方便食品。)
Chaplin sits down at the table and eats the shoe with a knife and fork. 卓别林坐在餐桌前,拿起刀叉吃那只皮鞋。
参考资料:俞才抡《高考英语能力突破•词汇》上海外语教育出版社