Answer:
thus or therefore
Explanation:
The sentence above requires a "connector" in order to connect two independent clauses.
First clause: Douglass believed that education was important.
Second clause: He taught other slaves to read the New Testament at a weekly church service.
A connector in the form of "conjunctive adverb" (thus/therefore) was used because the clauses show a transitional expression. It meant that Douglass wanted people to become educated and to value education. This is the reason why he taught the slaves to read.
