By the [point in time] + past simple / past continuous / past perfect

Question

I've come across two sentences in "My Grammar Lab Advanced" that I found really confusing and made me want to reevaulate my understanding of the expression "by the + point in time" used in conjuction with various past tenses. The sentences are the following:

By the middle of 2008 many parts of Europe experienced / were experiencing / had experienced the worst economic recession for decades

and the second one

By the third month of the war rebel forces took / were taking / had taken most of the province

My understanding of the expression By the + point in time (e.g. By the fourth day of the struggle) is that it's quite similar to the expression By the end of + point in time (e.g. By the end of 2010) which, according to a vast majority of English grammar coursebooks should be complemented with the Past Perfect (e.g. By the end of 2010 we had managed to save a lot of money). My question is: are all the three tenses (the Past Simple, Past Continuous, Past Perfect) correct in both sentences? Is there any rule governing the proper use the expression By the + point in time with the three above-mentioned tenses? I'm pretty lost here, any help would be much appreciated.

Answer 1

The verb tense depends on the time clause, the subject, and the object. Even though past perfect might be the most common choice for "By the + point in time" sentences, there are certainly cases where past continuous can be used.

In the first sentence, the most correct option is the past continuous, "were experiencing."

By the middle of 2008 many parts of Europe were experiencing the worst economic recession for decades.

The object of the verb, economic recession, is something that takes place over a relatively long period of time (vs. a crash, for example)--it's an ongoing process. Also, the subject is vague and involves many separate entities, so even if a recession was definitely over for one (past perfect), for another country the recession could still be happening.

Past simple would never be the correct choice because the time clause "By the + point in time," indicates some separation between the point in time where it is located and the period of time when the event in the main clause occurred. You're saying that by this time, some event already happened and is over, or started to happen and is still happening.

In the second sentence, the correct tense is past perfect:

By the third month of the war rebel forces had taken most of the province.

You wouldn't use past continuous here for contextual reasons. The sentence "By the third month of the war rebel forces were taking most of the province" doesn't make sense. "Most of" specifies an amount of the province under rebel control, implying that the outcome has already been seen.

Answer 2

All three uses are correct.

Past indicative tense: "experienced" and "took"
Past progressive tense: "were experiencing" and "were taking"
Past-perfect tense: "had experienced" and "had taken"

The Chicago Manual of Style and the University of Oxford Style Guide are both great resources for checking syntax.