In other words, they’re singular and plural at the same time. And since verbs are supposed to agree in number with their subjects — one cat is, two cats are — the roughly 200 collective ...

When both nouns joined by “or” are singular, the verb form is easy: It’s singular, as we saw in “Ned or Nancy is.” When both nouns joined by “or” are plural, the verb is plural ...

B) Singular knots: opposite crossovers (one formed by the right string passing on top of the left string and the other inverse) are called singular points (star).