is "had become" and "have known" passive voice?
450319
No, it's just the perfect tense.\n\nPassive is switching a sentence into something like "The car had been driven by me" when you can just say "I drove the car."\n\nYou're just stating that these particular things happened in the recent past.
58512
Has is present tense. Had is past tense.\n\nHe has friends. (now)\n\nHe had friends. (past)
453896
Passive Perfect Participle\nPPA = Perfect Participle Active
1127943
The various proposed answeres are wrong when they suggest that 1 and 3 are incorrect. they are not common, and most people don't now use them, but they have been used in speech and in writing.\n\nEnglish verb tenses, particularly the complex ones (with the helper verbs), are numerous and often only subtly different. In this case the distinction is between a fact of reality (it can't have been <whatever> which would presumably be discovered when actually confronting the facts  and a conditional conclusion disproved. \n\nHis igorance in 1 is the fact,  and the door's locked condition is the fact in 3. For 2 and 4 some investigation suggests that it ould have been impossible that <whatever> because of something which turned up later. It turned out that he knew in 2, while something shows that contrary to expectation, some new fact shows that the door being locked is impossible. \n\nSome languages, like Navajo, include in verb tneses information about  the nature of the agent which caused the <whatever> we are observing. One tnese for a fence knocked down by a windstorm, another for the same fence, knocked down to the same condition, by a living agent (cows, maybe). Englich complex tenses tend to convey information about probabilities and expectations as well as time values and conditionality (eg, subjunctive). for those who master them, the English tense system is a supple and graceful tool.
401701
It is past tense, you are maybe thinking that 'to go' implies current and active, this is true but the context of the rest of the sentance gives you the tense... 'They let us...', 'They did not let...', 'I let him go' etc (All past tense)\n\nLet without a modifier like 'will' or 'am/are' is past tense 'They will let us go'(future), 'They are letting us go'(present).\n\nThat's a good point!... Is the question mark meant to be inside the quotes? if so that makes it a question (not great grammar tho') probably should read 'They have let us go?'
386261
If you wish to say the equivalent of\n"I have relinquished.."\nyou would say "I have forgone" (or foregone)\n\nIf you are saying "I relinquished.."\nyou would say "I forwent" (or forewent)
980795
Okay, here is what it means if a sentence is active or passive.  Active sentences are ones in which the subjects are DOING an action.  Passive sentences are ones in which the subjects are RECEIVING an action.  For example:\n\n#1. Passive: their lives may have been spared...\n      Active: ______ (subject -- who?) might have spared their lives.\n\nI'm not sure how exactly to change the other sentences since I have not read Hamlet, and I need more context to help you.
356820
if you're talking about fell, as in to fell a tree, then the past tense is felled. If you're talking about fall, then fell is the past tense.
1098557
Both sentences are quite OK as they stand.  Changing the tenses - as some answerers have suggested - would also subtly change the meanings.\n\nE.g.\nElsie disagreed with the group and resigned.  (She did both these things yesterday or last week).\nElsie disagreed with the group and has resigned.  (She disagreed with them yesterday and has just resigned very recently as a result).\n\nSharon has set her cap over her eyes and (has) laid a towel over her legs to protect herself from the sun.  (The 'has' in brackets is understood - this is called ellipsis.  This sentence suggests that you are sitting next to her and telling someone - perhaps by phone - what she has just done.)\n\nSharon set ... (The change of tense suggests that she did both things yesterday or last week etc.  This is a more 'usual or bland' meaning).\n\nTo lay a towel over your legs - or any other part of your body - is perfectly grammatical (past tense = laid a towel ...) whatever anyone else says.
777254
write in the passive and not active voice.
318657
depends on how you use it....\n\nI was lying down.\nHe is laying down.\n\nOne is past tense the other is present tense.
770224
"Liaison" is a noun, not a verb. Nouns do not have past tenses.\nThe verb from "liaison" is "liaise" and the past tense of that would be "liaised".
576195
I have learned to avoid the repetition of the same word in a sentence of English at school. "know" and "music" are duplicated in the sentences you wrote. You should say\n\nKevin knows much more about music than I.\nKevin knows music more than I.\n\nBut I think both are grammatically correct.
4433
He is smarter than I. \n\nThe key is than. You have ended the sentence with a than-clause, but, according to proper grammar, you must have a subject and verb to have a clause. And you do. Basically, you have removed the rest of the words from the clause because they are understood. Theoretically, the sentence should be "He is smarter than I am smart." "..than I am smart" is the clause.   \n\nThis also works with as-clauses, "He is as smart as I." As odd as it sounds, you would finish that thought by saying, "He is as smart as I am smart." \n\nWhen ending a sentence with either a than or as-clause, you can always test it by finishing the clause.
439169
Verb form\npetted\npast tense and past participle of the verb to pet
1171484
Sorry, Dakota and Sarah are mistaken.  The use of the different tenses has nothing at all to do with who told me.\n\n#1 is the PAST tense\n#2 is the PRESENT PERFECT tense.\n\nThe first is used for something that took place at some definite point in the past.   Thus you can add a specific time:  "Last Thursday I heard."  (You CANNOT say, "Last Thursday I have heard..." )\n\nThe second -- the present perfect--   is trickier to get.   It is used for something that happened, or at least began at some "unspecified time" in the past.   It's the form you're likely to use to emphasize that you have had this experience (of hearing such a report).   You may use it when you want to say that it the experience took place several times, or even that it is continuing right up to the present.\n\n(In other words "have heard" is vague NOT about the source, but about the TIME.)\n\n\nFor examples of these basic uses of the present perfect, one of more of these may help:\nhttp://www.englishpage.com/verbpage/presentperfect.html\nhttp://esl.about.com/library/grammar/blpresperfect.htm\nhttp://web2.uvcs.uvic.ca/elc/studyzone/330/grammar/upperf.htm\nhttp://www.eclecticenglish.com/grammar/PresentPerfect1A.html
672974
Go buy a copy of "500 Latin Verbs Fully Conjugated in all the Tenses".  I'm too lazy to walk all the way downstairs and to the other end of the house to get my copy or else I'd tell you.\n\nEDIT:  OK, I'm awake now, lol.  Since "go" is an intransitive verb, there is NO SUCH THING as a passive form of it.  LOLOLOLOL