aspect none rare casualwritten
keep on ~ing / left in a continuing state
Builds on 〜続ける
A full written guide for keep on ~ing / left in a continuing state is on the way.
This point is mapped in the grammar Path, but its examples, formation table and usage notes haven't been written yet. The fastest way to learn it now is to meet it in real sentences inside Jengo.
See this grammar in real sentences
Jengo shows each grammar point the way you actually meet it: inside real Japanese sentences, so it sticks instead of staying an abstract rule.
Study it in JengoSources Compiled with reference to A Dictionary of Intermediate Japanese Grammar. Editorial confidence: low.