When someone makes an assertion, the distinction between "how did you know" and "how do you know" seems to be that "how did you know" implies that the person in question is correct in their assertion. "How do you know" is normally an inquiry into the person's credentials, and often expresses that the assertion is incorrect and/or ungrounded. Does anyone know what the reason for this distinction is? Why does simply changing the tense of the verb change the implication so strongly? I suspect that, linguistically speaking, the "did" might be a different tense than the past tense, but I'm not sure what it is, or I could be entirely wrong.
Learn English – “How did you know?” vs. “how do you know?” distinction
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"Have been reading" is in the present perfect continuous tense. The present perfect and present perfect continuous do not require that the action has been completed. This tense is actually used to describe actions in the past that have a connection to the present. Either the action has been completed (approximately) now or it will continue — both options are possible.
The presence of for does not change the entailments of the present perfect progressive. I could say either of the following:
- I have been reading this book for hours, and I will keep reading until bedtime.
- I have been reading this book for hours, but now I'm watching TV.
In (1), the context says that the action is continuing, while in (2), the action has stopped. The pres. perf. continuous works in both cases. The common thread is that, in both sentences, the act of reading is described with respect to the present time.
One other thing: you might notice that the present perfect construction "have read" that you have in your example is not forming a connection to the present, but rather forming a connection to a future time. This is because of something special about when clauses that refer to the future, wherein the form is present tense (in this case present perfect), but the meaning is like the future tense (in this case future perfect: "will have read").
It is unfortunately common for writers to attempt dialogue in Early Modern English, even though they do not know this language. This typically results in a panoply of howlers: -th and -st added randomly to verbs, thee used as the subject of sentences and thou as the object, mine used before consonants, and vocabulary used in anachronistic senses.
There's really no substitute for reading widely in the language. It's easy to get hold of texts from the period via Project Gutenberg, Google Books, the Internet Archive and so on (editions often modernize spelling but usually leave grammar and vocabulary alone). The Historical Thesaurus of the Oxford English Dictionary is a useful tool for finding vocabulary that's appropriate to a particular historical period, or if your library lacks this work, then try Google Advanced Book Search by date.
It will pay dividends if you immerse yourself in the language even as you attempt to learn its rules, and so I recommend James Greenwood's Royal English Grammar of 1737, which says (page 60):
In Engliſh there is no Change at all made of the Verbs; except in
The Second Perſon Singular of the Preſent Tenſe, and in the Second Perſon Singular of the Preter Tenſe, which Perſons are diſtinguiſhed by the Addition of eſt; as, thou burneſt, thou readeſt, thou burned'ſt, thou loved'ſt. So likewiſe
In the Third Perſon of the Preſent Tenſe, an Alteration is made by adding the ending eth, or s, (or es if the Pronunciation requires it;) as, he burneth or burns, he readeth or reads. In all the other Perſons the Word is the ſame; as, I burn, we burn, ye burn, they burn. So, I burned, he burned, we burned, ye burned, they burned, &c.
If the Preſent Tenſe ends in e, the ſt is added inſtead of eſt, in the Second Perſon, and th inſtead of eth in the Third Perſon; as, I love, thou loveſt, he loveth.
Both your examples contain solecisms:
*He dideth walk to the store.
Use "he did walk". [For example: 1687 The Compleat Office of the Holy Week 249 Noe was a a juſt and perfect man in his generations: He did walk with God.]
Also, store meaning "a place where merchandise is kept for sale" is, according to the OED, an American usage first attested in 1731, so may not be appropriate for your period. Try shop instead.
*He walkedeth to the store.
Use "he walked". [For example: 1608 J. Donne ΒΙΑΘΑΝΑΤΟΣ (1648) 169 expoſing himſelfe to certaine danger when he walked upon the water.]
Best Answer
The changing of the tense indicates that, in the case of "did" the fact has been established as true in the past. The truth value having been set, the question is "how DID you (before it was set) know that it would turn out to be true?"
The question phrased in the present tense is a challenge -- the truth value has not been set as of right now (in the present) so the question is "since we haven't ascertained truth, how can you be sure of your assertion?"