People who know the book "1984" only:
what page is the quote "“for, after all, how do we know that two and two make four? or that the force of gravity works? or that the past is unchangeable? if both the past and the external world exist only in the mind, and if the mind itself is controllable – what then? ” on? i am doing an essay on totalitarian governments and need the
asap.
offering 70 points.

the bottom of the ocean

quite an interesting way to teach topic sentences, because the answer to this question is the best definition of a topic sentence that one can present, it is as if answering the questions taught you how to do it, this is some real teaching, it is terribly well-done.

the topic sentence in this paragraph is:

topic sentences writers stay on track and keep a paragraph from becoming an aimless collection of sentences about an idea.

which incidentally tells you what a topic sentence should be.