Present continous tense: I am living with my sister until I find an apartment.

[Aikuzo]

- I am living with my sister until I find an apartment.

You can just also have "I am living with my sister." as a complete sentence right? You don't have to specify something like 'until I find an apartment' to make it complete.
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I quit studying English years ago and have just come back to study the basics.

[Cerberus™]

That's right: I am living with my sister is fine as it is.