When is the English word "family" singular? When to use the plural?

Family is a noun, which means "family, family". When family is the subject, the predicate verb is sometimes singular and sometimes plural, depending on the specific situation. When we consider "family" as an abstract concept as a whole, the predicate verb is singular, and when we understand "family", the predicate verb is plural.

The use of the word "family":

1, I have a very big family. My family is a big family.

2、 ? The family is the basic unit of society. The family is the basic unit of society. ?

The whole family is ill. The whole family is ill.

The Spring Festival in China is a time for family reunion. The Spring Festival is a good time for family gatherings. ?

Our nation is a big family composed of five or six ethnic groups. Our country is a big family of 56 nationalities.