只有在表示“鸡眼”这个意思时是可数名词，在表示“谷物“或是”玉米“时都是不可数名词。所以”喜欢吃玉米”不用加s.
英语释义如下：corn,
noun
(BrE) [U] any plant that is grown for its grain, such as wheat; the grain of these plants: a field of corn ◆ ears / sheaves of corn ◆ corn-fed chicken
[U] (AmE) = MAIZE
See also CORN COB, CORN ON THE COB
[U] (AmE) = SWEETCORN
[C] a small area of hard skin on the foot, especially the toe, that is sometimes painful