het geheugen
het-wordmemory
/ɦɛt ɣəˈɦœyɣən/
de geheugens
This one you just learn — no rule points to het here.
Mijn geheugen is niet zo goed meer.
My memory is not so good anymore.
The de/het checker covers one word. The full platform covers vocabulary, grammar and all five DUO sections.