老 / 老是【lǎo / lǎoshì】

老 and 老是 before a verb mean "always, keeps on", with a complaint built in. They're spoken, and they go after the subject.

老是 and 老 mean the same; 老 alone is shorter and a little more casual.

With a negative

老不 and 老没 give "never" – again as a complaint.

In questions and orders

怎么老是 asks why something keeps happening; 别老 tells someone to stop.

老是 or 总是

总是 is "always" with no attitude, so it suits a good habit. 老是 on a good habit sounds as if you resent it.

他老是帮助我 would sound as if the help gets on your nerves.

Position

Like other adverbs, 老是 goes after the subject.

• × 老是他迟到 → 他老是迟到