Had hitherto knowi 13. The author's primary purpose in this passage 15. In lin
is to:
(A) explain the timing of a pivotal
(B)
development.
(B) describe the discovery of a limitless
(D)
commodity.
(C) praise the acumen of a famous
industrialist.
(D) compare the United States to less
scientifically advanced nations.

because i have already answered your question several times, answering it again would be superfluous.

by elena

active voice: my father cut the tree.

passive voice: the tree was cut by my father.

active voice: people buy newspapers every day.

passive voice: newspapers are bought (by people) every day.

active voice: people have been using movies as political propaganda since world war ii.

passive voice: movies have been used as political propaganda since world war ii.

active voice: donna gave me my birthday present.

passive voice: i was given my birthday present (by donna). / my birthday present was given to me (by donna).

active voice: mom will leave the keys on the counter.

passive voice: the keys will be left (by mom) on the counter.

the words in parentheses are the agent of the passive voice and can be omitted when obvious, generic, or simply unnecessary.

answers may vary, but my guess based on my personal education it has alwats been 3 or 4