SAT: Tense questions...

I have two SAT tense questions. I’m happy to hear your thoughts.

(1) Scientists are still trying to account for sudden deaths among gray whales but (sepculating) that several events prevented them from gorging on the tiny shrimplike creatures that they typically feed on.

==> Which verb form would you select between speculating and speculate?
I would go with “speculate” because it sounds right. But on the second thought, “scpeculating” would also make sense, asuming that the verb “are” has been omitted from “scientists are speculating.” So the full sentence would read like “Scientists are still trying … but (are) speculating …”
What do you think guys?

(2) In 1972, you could have bought a gallon of gasoline for 40 cents, but a year later (would have paid) twice as much for the same amount.

==> I don’t understand the meaning of this sentence. Does this mean “you could not buy (even though there was a possibility of doing so) a gallong of gasoline for 40 cents in 1972, but a year later you did not pay less than 80cents?” What does this mean? Why all the “conditional tenses”?

How about using “would pay or paid” instead? would it sound much better?

thanks.

1-- ‘Speculate’. ‘Are’ cannot be omitted from ‘are speculating’.
2-- A gallon of gas cost 40 cents in 1972 and 80 cents in 1973.

thanks for the quick answer.

One more quick question: (At the same time) the Wright brothers (were becoming) famous for their early flights, Fong Yue built and flew biplanes that demonstrated his own ideas about airplane manufacture.

(1) isn’t “become” the stative verb? So it should be used in simple past form (became)?
(2) “at the same time” necessay here? why not “when”?

1-- Yes it is stative, and no, stative verbs can be used in progressive aspect in various contexts (as here).
2-- Not necessary, but good style: in emphasizes the simultaneity of the two events.