The English third person plural pronoun set is the only English pronoun set that is common gender. The first and second persons are also gender-neutral but express dual gender. Meanwhile, the third person singular pronouns come in masculine, feminine and neuter variants.
A quick test for common gender involves seeing which third person singular pronouns can refer to the noun in question. If all three pronoun sets can be used (i.e. he, she and it), then it's common gender.
Use of gender-neutral language is often encouraged, especially in formal contexts.
Using plural forms is often common gender/gender-neutral as well, while retaining stylistic prescriptions. e.g. "a teacher often finds that he/she has high TTT" -> "teachers often find that they have high TTT".