(1) In the nominative, as the subject to the verb =olla= in affirmative
sentences. It then denotes the necessity or propriety of performing an
action, the subject of which is put in the genitive. =Minun on tämä kirja
lukeminen=, _I ought to read this book_, or literally, _this book is a
reading for me_. =Meidän on tottuminen siihen=, _we must get used to it_.
=Tehty kauppa kiittäminen, tekemätön tietäminen=, _one should praise
a bargain which is made, but enquire into one which is not yet made_
(prov.). Copious examples can be found in Kal. xxiii. 61, =Tapa on uusi
ottaminen, Entinen unohtaminen=, etc.
(2) The partitive is, agreeably to general rules, used in a similar sense
in negative sentences, or interrogative sentences implying a negative.
=Ei ole minun tätä kirjaa lukemista=, _I need not read this book_. =Ei
koiraa karvoihin katsomista=, _one must not judge a dog by his coat_. =Ei
pojan isäänsä opettamista=, _a son should not teach his father_.
In such phrases as =minulla on vielä paljo sanomista=, _I have still much
to say_, the partitive depends on the word =paljo=, just as it does in
such a sentence as =paljo rahaa=, _much money_.
_Infinitive V._
This infinitive is only a diminutive form derived from infinitive III. As
a rule, it is only used in one case, the adessive plural, to denote an
action on the point of taking place (cf. infinitive III, E. 1). It always
takes the pronominal suffix. =Olin työtä alottamaisillani=, _I was on the
point of beginning to work_. =Juna on juuri lähtemäisillänsä=, _the train
is just going_. =Aurinko oli katoamaisillaan=, _the sun was just going
to set_. =Yhtiö on muodostumaisillaan=, _the company is on the point of
being formed_. =Mies oli kaatamaisillaan puuta=, _the man was on the
point of felling the tree_.