Hi Mike! I know this question has been asked before by someone else but I am still confused: (To stand in) Persepolis in modern Iran and look out, as Darius the First (must have done), at the immense (sweep of fields and mountains) is (to grasp) the vastness of the ancient Persian Empire. (No error)
When I looked in a grammar book that I had, I found out that “must” is in present tense and “had to” is the correct past tense. Since Darius the First clearly belongs to the past, I’m very confused.

Don’t we use the present perfect tense if something happened in the past and is still happening today/now?
First run in 1867 and still taking place every summer, the Belmont Stakes, a horse race for thoroughbred three-year-olds, [was] one of the oldest races in the United States.
a)was
b)is
c)were
d)are
e)has been
According to the collegeboard, B is the answer? Isn’t it supposed to be E? Thank you Mike.

inspired by a love of birds, Nancy Yi Fan (has begun to write) her novel ‘Snowbird’ when she was in fifth grade.
a)same
d)began writing
why doesn’t has begun work in this case? is it because the action was presumably ended in past? can i get explanations for difference between has and simple past?

Hello!
Now that Michiko (A) FINSIHED the research, she feels B )REASONABLY CONFIDENT C) ABOUT WRITING her paper on the D) RISE OF the progressive movement in the United States.

The answer explanation says it has to be Now that Michiko has finished the research because it continues until the present. But shouldn’t the answer be “had finished” since she’s literally finished with it?

Thank you!

At the end of every class a crowd of students would gather around the professor to ask questions for which there had been no time during the class period.

Why should it be “had been”?

Marathon racing (has become) increasingly popular among amateur athletes in the last few years.

Why is this sentence correct? Isn’t “last few years” past, not present perfect?

Eighteenth-century botanist Carl Linnaeus showed that bananas could be grown in Europe if farmers (will simulate) Asia’s monsoon climate by letting the soil dry out and then flooding it with water.
A) will simulate b) had simulated c) simulated d)who simulate e) simulating

Although the author HAS PRESENTED (A)her book to the publisher AS A(B) fact-based memoir , she later confessed that it had been ENTIRELY(C) FABRICATED (D).

my answer: E correct answer:A

Some of workers A-who resent- the supervisor’s authority B- would probably- feel uncomfortable C-if- they were to acquire the independence that D-they demand-.
I thought that ‘they demand’ would be ‘demanded’ but the answer says there is no error. Why demand is correct? Is it because the ‘if’ part is in subjunctive mood not in past tense? and the demand parallels with resent?

Thanks 🙂

During the Spanish Civil War, many Catalan writers were forced into exile and, with the exception of Salvador Espriu, ceased to publish new works until after democracy (had been) established.

Answer is No Error. Why? I thought “had been” needed to be changed to “was” because the sequence is:

1) Catalan writers ceased to publish new works
2) Democracy was reestablished.

Since (2) occurred after (1), shouldn’t it be “was” instead of “had been”?

Hello. Hope you are doing well. Could you please explain the following questions?

‘[If there were] a power failure, the hospital will run on electricity from its own generators, which can operate for 200 hours.’

[If there were] is incorrect and should be replaced by [Should there be]. Can you please explain why?

He records the most influential songs, (which includes) such classics as “Rave On” and Peggy Sue.”

Should “includes” be changed to “include” since it is referring to the plural “songs”?

Because his experience in the naval medical corps had been rewarding, Bob applied to medical school after he (was discharged) from the navy.

The answer is No Error, but shouldn’t the parenthetical phrase be changed to “HAD BEEN discharged” since it is with “after,” indicating a past perfect tense?

In this sentence: “Some scientists believe that the species known as White’s tree frog is able to control the amount of water that is evaporated through its skin and that its body temperature being controlled in this way.” why is “being” grammatically incorrect?

Developed for the european space agency in the 1990s, the rockets of the ariane 5 class *did not yet prove their* reliability as of 2003.

A) did not yet prove their
D) had not yet proved their
E) has not yet proven their

Why is the answer D?

Why is the answer not E? Shouldn’t the answer include “proven”? Shouldn’t the answer say “has” because “as of 2003” indicate present perfect?