世話: care requested and help received
Compare asking a younger sister to care for a cat with receiving help from senior colleagues. Read the care target and the recipient of help, while keeping a request separate from completed care.
Asking someone to care for the cat
「旅行中の猫の世話を妹に頼んだ。」 (I asked my younger sister to care for my cat while I traveled.)
The care concerns the cat during the trip, and the younger sister is the person asked to provide it. The sentence reports the request.
Help received from senior colleagues
「新人のころは、先輩にずいぶん世話になった。」 (I received a great deal of help from senior colleagues when I was new.)
The speaker received help while new at work. 世話になる describes the relationship from the side of the person who benefited from that help.
Following the direction of care and help
The first scene concerns care requested for the cat; the second concerns help received by the speaker. Identify the care target and the recipient of help rather than treating both scenes as the same event.
Asking the sister does not establish that she finished caring for the cat. Help from senior colleagues also does not, by itself, specify a financial debt or an amount to repay.
Does asking the younger sister to provide 世話 for the cat mean she has already finished caring for it?
Show the answer and why
No completed care is reported by the request alone. Whether she carried it out is separate information. In the other example, 世話になった describes the help the speaker received from senior colleagues.