Grammatica - loco

12
Conjunctions
300
It is also used to translate ‘when’ in subordinate clauses when the verb is
in the present, future or perfect tense. In this case it can be replaced by
als:
Wanneer (als) het regent, blijf ik thuis.
When it rains I stay at home.
It can only be used in a clause with the verb in the imperfect or pluperfect
when it means ‘whenever’, otherwise toen is used (see below). This wanneer
can also be replaced by als:
Wanneer (als) hij dan thuiskwam was zij altijd boos op hem.
Whenever he came home she was always angry with him.
Als, apart from replacing wanneer in instances such as the above, also
renders ‘if’ (but not ‘if’ which means ‘whether’, see of), in which case a
slight ambiguity as to whether als means ‘if’ or ‘when’ can arise, but this
does not worry the Dutch:
Als het regent, wil ik thuis blijven.
When/if it rains, . . .
See 12.2.1.9 below for als as an abbreviation of alsof. See chapter 13 for
use of als as a preposition.
Toen replaces wanneer/als when the verb is in the past, i.e. when the
meaning is ‘when on one occasion in the past’, but wanneer/als are used
when the verb is in the imperfect and the meaning is ‘whenever’, i.e. ‘when
on repeated occasions in the past’:
Toen hij thuiskwam, was ik al weg.
When he got home, I had already left.
Compare:
Wanneer (als) hij thuiskwam, was ik altijd al weg.
When(ever) he got home, I had always already left.
Note: There is also an adverb toen ‘then’ which should not be confused
with the conjunction toen ‘when’ discussed here (see 10.3.21.11):
Toen ging hij weg.
He then left.
Toen hij wegging . . .
When he left . . .