Yes, 'managed to do something' means 'succeeded in doing somthing, especially something difficult'. If you say "I managed to write a blog yesterday", you mean you succeeded in writing a blog or were able to write a blog yesterday.
You can't say "I could write a blog yesterday", though, because 'could' is not used to talk about particular ability in the past (on one occasion).
You can say, however, "I could eat a whole cake when I was little" - 'could' can be used for general ability in the past.
'Couldn't' (the negative), on the other hand, can be used for both general and particular ability in the past, you can say, for example, "I couldn't write so well when I was young" (general ability) or "I managed to write a blog yesterday, but I couldn't proofread it" (particular ability).
Comments
Great, Onee!
I'm glad you managed to publish a poem challenge - sorry, I failed to give it a try! Keep it up!
Dear Expector,,
Thank you so much for sharing this with us. Now I know how to use 'managed to' and 'could' very well. I hope I won't forget since I'm forgetful. hehe...
I managed to do something important last month, but I couldn't post many comments in this site. Keep sharing useful tips with us, doc. I'm thinking about something to remember them. :)
Many thanks, Nadya, Shoba, Risty!
I'm pleased that all of the sentences you made are correct. Keep it up!
Hello Sir Expector, let me try to grasp this knowledge and write my examples, based on my understanding,
I managed to organize my friend's wedding last Thursday, but I couldn't remember where did I put my art kit.
I could have explained well the meaning of Nirvana fallacy during college days.
I couldn't decrypt the story behind the movie I watched last night.
I managed to arrange/connect all the necessary peripherals on our office server.
Thanks Sir. Educational indeed. :)
I didn't know that using "could" to talk about particular ability in the past was wrong. Thank you very much for sharing this important tip, Sir Expector!
I was able to declutter my closet yesterday or I managed to declutter my closet yesterday.
I could run very fast when I was a child.
I couldn't finish cleaning the garden last Saturday.
I couldn't talk in Sinhala when I was a child.
Perfect! You always come up with great teaching tips.