を兼ねて goes after a noun and means one action serves that purpose too: "partly as", "also for". The noun is the extra purpose, and the rest of the sentence is what you actually do.
。
I went shopping, partly for the walk.
。
I took some sweets along, partly as a way of saying hello.
、。
I watch the news in Japanese every day, partly to study.
Two purposes can go in together with ….
、。
I went running in the park, both for the exercise and for a change of scene.
を兼ねて or ついでに
adds a second action because the first one gives you the chance: you are out shopping anyway, so you drop into the bookstore. を兼ねて has one action that you planned to serve two purposes.
、。
While I was out shopping, I stopped by the bookstore.
、。
I cycle to work every morning, partly to lose weight.
Usage notes
These go beyond を兼ねて joining two clauses.
Before a noun
To describe a noun, use .
。
I went on a trip that was also a tour of inspection.
。
I'm going to Paris on a business trip that doubles as a holiday.
Doubling as
With or as the main verb, one thing does the job of another: a room that is also a study, a person who holds two posts.
。
This room also serves as a study.
。
The president is also the head of sales.
Not 〜かねる
after a ます-stem, as in
, is a different pattern: a polite "cannot". It is written with the same kanji but takes a verb, not a noun with を.
Lingaku