"Vääntää" ja "väännellä" ero? Miten selität englanniksi?

Tässä istuskelen, ja yksikseni yskiskelen.

Kyseessä on kontinuatiiviset ja frekventatiiviset verbimuodot, joista enemmän esimerkiksi seuraavissa:

http://www.kotikielenseura.fi/virittaja/hakemistot/jutut/1975_153.pdf

http://epa.niif.hu/02400/02414/00001/pdf/EPA02414_StudiFinnoUgrici_1_1995_083-092.pdf

Ei ihan helppoa, mutta yritetäänpä:

Frequentative verbs

The suffixes ellA : ele- (or for some verbs illA : ile-) and skellA : skele- are used to derive verbs that mean performing the action expressed by the base verb in a frequent or continuous manner. A simple example is kysellä : kysele- (to ask questions), derived from kysyä : kysy- (to ask); it simply means repeated action of asking.

For example, from istua : istu- (to sit) we get istuskella : istuskele- (to sit about [frequently in some places]; to sit back [doing something]). Such verbs can be called frequentative or continuative. For some verbs, both suffixes can be used, possibly with no clear difference in meaning. For example, from olla : ole- we get both oleilla : oleile- and oleskella : oleskele-, which both mean staying around for some time, though the former might specifically refer to spending one’s time without doing any work. For most verbs, however, just one of these suffixes is in use.

For many verbs, these suffixes also imply reflexive or reciprocal meaning. That is, the action may have its subject as the implied object, or the verb may express mutual action. For example, from harjoittaa (to practice; to exercise) we get harjoitella, which means practicing in some sport or skill, implying both repeated action and practicing oneself.

Many derivations of this type have a more or less specialized meaning and need not have any frequentative or continuative meaning. From rakastaa : rakasta- (to love), the verb rakastella : rakastele- (to make love) has been derived, and it means sexual intercourse that need not be repeated or continued. From vääntää : väännä- (to turn, to wind, to twist), we get väännellä : vääntele-, which may have a concrete meaning (to repeated turn something), but more often it has a figurative meaning, as in Hän väänteli sanojani (He twisted/distorted my words).

There are also verbs that apparently contain one of these suffixes but have no real base word. For example, suudella : suutele- (to kiss) could be analyzed as a derivation of suutaa : suuda- (which would be related to suu “mouth”), but no such verb is known.

Due to the great variation in meanings, verbs of these types need to be learned separately. If you see a word like vastustella and you do not know it, you might guess that it is a derivative of vastustaa : vastusta- (to oppose) and think that it could mean “to oppose repeatedly, to resist”. And here your guess would be right, but it would be better to check it from a dictionary. If you similarly thought that arvostella, being a derivative of arvostaa (to appreciate, to respect), means repeated appreciation, you would guess wrong; it means criticizing, often implying negative (unfavorable) rather than positive criticism. The explanation is that arvosta, derived from arvo (value), generally means giving some value to something, estimating the value of something.