They say he can teach almost anything in this world.

It is said that almost anything in this world can be taught by him

It was said that almost anything could be taught by him

They say almost anything could be taught by him

They say anything almost will be taught by him

All of the above

Active Voice: They say

Passive Voice: It is said

Present Indefinite Tense

Active Voice: Subject + Verb + Object

Passive Voice: Object + is/am/are+ third form of a verb + by + subject.