According to what you've read by ngugi wa thiong'o what must colonizers do in order to control a colonized people mentally

The colonizers should suppress the culture, language and religion of the colonized and impose their own culture, language, religion and customs.

Explanation:

The settlers should think only of themselves, in their cultures, their traditions and customs, religion and language, they were instructed to see the culture of civilized peoples as something inferior and because of this should disappear, they were also taught to impose their culture , belief and language as a form of domination of the colonized peoples

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