wǒ zài zhè gè chéngshì zhù le sìshí tiān le.

I have lived in this city for forty days.

Breakdown of wǒ zài zhè gè chéngshì zhù le sìshí tiān le.

• 我wǒ: I
• 这zhè: this
• 个gè: noun classifier

Questions & Answers about wǒ zài zhè gè chéngshì zhù le sìshí tiān le.

Why are there two 了 (le) in this sentence? What does each one do?

In 我在这个城市住了四十天了, the two 了 play different roles:

1. The first 了 (after 住)

   • This is verb 了 / aspect 了.
   • It attaches to the verb 住 and works with the duration 四十天 to show that the action has already lasted that long.
   • Pattern: V + 了 + Duration (+ 了)

2. The second 了 (at the end)

   • This is sentence-final 了, which marks a new situation / change of state.
   • It roughly adds the idea of “now” or “already (by now)”:
     
     • Now it has been 40 days (that I’ve been living here).

Together, 住了四十天了 means:

• The action started in the past, has continued for 40 days, and the speaker is still living there now.

What is the difference between 我在这个城市住了四十天了 and 我在这个城市住了四十天 (without the last 了)?

• 我在这个城市住了四十天了

  • Implies: I have (already) been living in this city for 40 days, and I’m still here now.
  • Ongoing situation up to the present.

• 我在这个城市住了四十天

  • Normally understood as: I lived in this city for 40 days (and then I left / I’m not living there now).
  • Describes a completed period in the past.

So:

• With final 了 → ongoing up to now.
• Without final 了 → finished in the past (unless context forces a different reading).