In English, the tense of the main clause and relative clauses is usually relative to the time at which the sentence is spoken.
I waited until the bus came.
You use the past tense on both verbs because both the waiting and the coming happened in the past. But while you were waiting, the bus hadn't come yet! So, relative to the action of waiting, the bus ...
In this sentence, the "main" verb is 「います」 or the whole verb phrase 「多くなっています」 at the very end. That is the only verb whose tense determines the tense of the sentence.
That means that you should not really be calling 「使った」 the "past tense" only because there is a 「た」 in it. ...
In both sentences, the main verb is 「食べます」 and the tense of the main verb is the tense of the sentence.
That means whether you use 「母親が持ち帰る」 or 「母親が持ち帰った」 as a relative clause to modify the 「もの」, it has no effect at all on the tense of the sentence itself, which is present. In ...
Absolute times are ones that stay where they are as time moves onwards, or to think of it another way they're the ones that you can circle on a calendar or measure on a clock. So "Tuesday" or "May 25th" or "4 AM" are all absolute times, and the ever-changing now will eventually catch up to them and then pass them.
Relative times are ones measured in ...
(Disclaimer: I am a native Japanese speaker, but not an expert of language)
I feel there is a slight difference in meaning between (a) and (b).
Sentence (a) is the natural choice in most cases because of the relative-tense rule you have described. But (b) may be used to describe certain situations:
Other people ...
When going to Thailand, I studied a little of Thai.
Because 行く refers either to the present or future, it means that I studied Thai BEFORE going to Thailand.
When I went to Thailand, I studied a little of Thai.
This has the exact same meaning as in English. I went to Thailand, THEN I studied Thai.
抜けたら has nothing to do with past tense.
According to "A Dictionary of Basic Japanese Grammar", page 452:
"たら is a subordinate conjunction which indicates that the action/state expressed by the main clause in a sentence takes place after the action/state expressed by the subordinate clause."
If Mr. Yamada comes, I will go home.
An absolute time or date is a time period that will refer to the same time, regardless of when it is mentioned. These are typically exact times (on the same day in the current timezone unless otherwise stated) or calendar dates. In Japanese these are usually marked with the に particle but this can be omitted in casual conversation. For example: