"He thinks that I am already sleeping."

Translation: Myslí si, že už spím.

[BoneheadBass]

My answer -- Myslí, že už spím -- was wrong, because I left out "si." But I don't understand when the verb should be "myslet si" and when just "myslet" is fine. If someone could explain, that would be great!

[VladaFu]

I think you can use both here. There is some discussion about the difference at https://forum.wordreference.com/threads/myslet-si-myslet.420478/

Presently we do accept On myslí and we do not accept just Myslí. It is probably just missing.

[BoneheadBass]

Thank you, especially for the link! Should I report it, so that it can be added, if I get this exercise again?

[VladaFu]

No, I have added it already, there was one previous report that suggested the same there.

[BrianSille2]

I had "myslí, ze uz spím" and it was accepted (with "Another correct solution"!) You say that "Myslí" alone is not accepted but the link you give appears to say that it is.

[BoneheadBass]

"Myslí, že už spím" is definitely accepted, and has been for at least two years. But we have no current report for this, so we can't tell you why it may have been rejected. Please use the Report button when you are reasonably sure that your answer is correct.

[BrianSille2]

I was not referring to my own answer which was correct and accepted but to a reply from VladaFu above which stated ..."we do not accept just Myslí." However that was 2 years ago!

[Mel32329]

Thank you - this link is very helpful - although the first few comments claim that there is "no discernible difference" between the two, another explanation seems clearer: "Myslet" is used when thinking ABOUT something, and "Myslet si" is when someone has an opinion on something. Would you agree?

[AgnusOinas]

There are (at least) four possibilities:

• The verb is followed by another clause "..., že..." - we can use both "myslet" and "myslet si" and I don't feel there's a difference.
• The verb is followed by "na" (to think of/about) - do not use "si", use non-reflexive "myslet".
• The verb is used as "to mean (+ by something)" - e.g. "Co tím myslíš?" (What do you mean by that?) - use non-reflexive "myslet".
• The verb is followed by an object, often "to", for example "Taky si to myslíš?" (Do you also think so/that?) - always use the reflexive "si".