We use each to talk about objects individually, and all to talk about objects as a
group:
▶️ The teacher gave a different task to each student.
(“each” emphasizes the individuality of the members of the group)
▶️ The teacher gave tests to all the students.
(“all” emphasizes the students as a group)
In a similar way, each of the members of a group emphasizes them as individuals,
and all of the members of a group emphasizes them as a whole:
▶️ Each of these chairs is hand-crafted.
▶️ All of the chairs are made in a factory.
▶️ The doctor spends an hour with each of the patients.
▶️ All of the patients think he’s a great doctor.
With “each,” we ALWAYS use the singular form of the verb:
▶️ Each of these chairs are is hand-crafted.
= Each chair is hand-crafted.
▶️ Each of the patients were was seen by the doctor.
= Each patient was seen by the doctor.
Sentences with “all of” use the singular form of the verb if the noun is singular, and
the plural form of the verb if the noun is plural:
▶️ All of the beer is imported.
(beer = singular)
▶️ All of the bottles are recyclable.
(bottles = plural)
▶️ All your advice was excellent.
(advice = singular)
▶️ All your suggestions were excellent.
(suggestions = plural)