Vocabulary is a concern. Particularly, when we want to know alternative yet appropriate ways of expressing an idea/thought/opinion. From internet, I could find a list of expressions. It is not a copyright content, and I must thank the anonymous contributors to the list.
Generalizing: as a general rule, as a rule, in general, generally, normally, on the whole, usually
Explaining: in other words, that is, this means that
Express certainty: it is certain that, there is no doubt that, I am confident that, certainly, definitely, clearly, undoubtedly, presumably, will, is, should
Express probability: it is probable that, it is likely that, probably
Express possibility: can, may, it is possible that, could, might, might possibly, possibly, perhaps
Express doubt: it is doubtful that, maybe
Express improbability: is improbable, is unlikely, it is uncertain
Express impossibility: impossible, cannot, can’t, will not, is not
Draw attention: it is worth noting that, it should be emphasized that, it should be highlighted that, it should be underlined that, in particular, especially, mainly, chiefly, mostly, it should be pointed out that, it should be noted that, it should be remembered that, it is worth stressing that, is vital, is crucial
Contrasting two points: however, but, in spite of, despite, in spite of the fact that, despite the fact that, nevertheless, nonetheless, instead, conversely, on the contrary, by contrast, whereas, while, whilst, although, even though, on the one hand, on the other hand, in contrast, in comparison with, but, yet, alternatively, the former, the latter, respectively, all the same
Giving alternatives: there are two possibilities, alternatively, the one, the other, either, or, neither, nor, in addition, not only, but also, worse still, better still, equally, likewise, similarly, correspondingly, in the same way, another possibility, in a similar vein, as well as, furthermore, moreover, also, although, again, what is more, besides, too, as well as
Giving examples or introducing illustrations: for example, for instance, to name an example, to give an example, is well illustrated by, a case point is, such as, such, one of which, illustrates, is an example of this, is shown by, is exemplified by, is illustrated by
Stating sequence: first of all, first, firstly, second, secondly, thirdly, fourthly, now, then, next, finally, to complete, after that, 1, 2, 3, last, lastly, furthermore, to begin with, moreover, in addition, to conclude, afterwards
Reformulate the same point: in other words, to put it more simply, to put it differently, it would be better to say
Stating consequences: so, therefore, as a consequence, as a result, now, consequently, because of, thus, for this reason, then, this is why, accordingly, hence, given this, with reference to, given, on this basis, is caused by, causes, due to, has the effect, affects, the reason for, because of this, if, then, results in, leads to, produces, owing to, through, as, since, because
Stating purpose: in order to, so that, so as to, to
Giving the method by which something happened: by …ing, by (noun), by using
Stating surprise about something unexpected: besides, however, nevertheless, surprisingly, nonetheless, notwithstanding, only, still, while, in any case, at any rate, for all that, after all, at the same time, all the same
Summarizing: to sum up, in summary, to summarize, in brief, altogether, overall
Reaching a conclusion: I conclude, I therefore conclude, reached the conclusion that, it is concluded, therefore, for this reason, then, thus, in conclusion, to bring it all together
Listing components: distinct factors, comprises, consists of, constitutes, is composed of, may be classified, may be divided, can be distinguished
Giving definitions: (something) is, means, describes, is defined as, is used, is concerned with, deals with, relates to, involves, signifies, consist of
Approximating results: is just over, is just under, a little over, a little under, about, approximately, nearly
Qualifying comparisons: considerably, a great deal, much, very much, rather, somewhat, significantly, slightly, scarcely, hardly, only just (bigger than); exactly, precisely, just, virtually, practically, more or less, almost, nearly, approximately, almost, not quite, not entirely (the same as); totally, very, completely, entirely, quite, considerably (different from); is similar, is dissimilar, is different
Qualifying frequency: never, rarely, sometimes, usually, often, always, generally, on the whole, frequently, occasionally, hardly ever, seldom
Qualifying results: under no circumstances, mainly, generally, predominantly, usually, the majority, most of, almost all, a number of, may be, some, a few, a little, fairly, very, quite, rather, almost
Qualifying change: no, minimal, slight, small, slow, gradual, steady, marked, large, dramatic, complete, steep, sharp, rapid, sudden (rise, increase, fluctuation, decrease, decline, reduction, fall, drop, upwards trend, downwards trend, peak, plateau, level off)