019 Usage of the modal verb 'would'

What part of speech is 'would' ?
'Would' was originally a past tense of the auxiliary verb (supporting verb) 'will'.
It was particularly useful in reporting speech, where the reporting verb was in past tense.
e.g. : He said that he would come.
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'Would' is a modal verb.
'Would' indicates past habit. 'Would' here, nearly means = 'used to'.
He would, during his adolescence, go to a free library and read volumes of old newspapers for hours together.
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Is it correct to say : "I would like to speak to Mr....."
The speaker, is indicating his preference here. He is expressing his desire or wish. A simple present tense usage like :
"I wish to speak to Mr....."
"I desire to speak to Mr...."
seems to be sufficient. The wish or desire is to get fulfilled at some time later, say some minutes.
"I shall like to speak to Mr....." may, perhaps, be sufficient.
But "would - the past tense form of 'will' " has entered the arena to express a wish.
------>>'Shall like to speak to Mr.', 'will like to speak to Mr.', 'would like to speak Mr. ...' etc. have some condescending tone. This may probably go well when a superior speaks to some subordinate.
------->> A more polite approach appears to be, to say : 'Please permit me to speak to Mr.....'. We can also go for other choices such as : 'May I speak to Mr.... ', 'Can I speak to Mr. ....' etc.

Compare the usage of 'would be' with the attributive adjective 'prospective'.
The attributive adjective 'prospective' has a positive connotation. It indicates the future prospects.
We can use would-be also as an attributive adjective. But, somehow, this adjective has derived a negative connotation of frustration and non-fulfillment.
e.g. 'would-be holliwood film star'. (Somebody wanted to go to holliwood and become a star; but apparently did not succeed.)

How about the usage of 'would have been' ?
'Would have been' too has a similar negative connotation. We get an indication of non-fulfillment.
e.g. Ms. Clinton would have been the President of United States, had she succeeded in getting the Democratic Nomination.

Modal verbs are supporting verbs (also called auxiliary verbs). They indicate the manner in which the speaker intends the action of the verb used by him is to have its effect. The verb may indicate a duty, ethical obligation, possibility, impossibility, probability, necessity, compulsiveness etc.