Writing simple sentences: capital letters and full stops

What makes a sentence

An English sentence needs a subject and a verb: The cat sleeps. A group of words with no verb — the big black cat — is not a sentence, however long it is.

Capital letters

Use a capital at the start of every sentence, for the word I anywhere in a sentence, and for names of people, places, days and months: Monday, March, Nam, Hanoi. Days and months are the ones learners forget most, because Vietnamese does not capitalise them.

End punctuation

A statement ends with a full stop, a question with a question mark, and a strong feeling with an exclamation mark. Every sentence must end with one of them — a missing full stop is marked as an error even when the English is perfect.