AOL: All the Light We Cannot See boss says Mark Ruffalo's "soulful warmth" took scenes to new level
All the Light We Cannot See has just arrived on Netflix – and the TV show's director and co-executive producer Shawn Levy has praised Mark Ruffalo's performance and Hugh Laurie has hit the streaming ...
All the Light We Cannot See boss says Mark Ruffalo's "soulful warmth" took scenes to new level
Many nouns describing attributes, like "security" or "tact", cannot be used with "be of". (Google books gives a few instances for "be of security"; it seems to have been used occasionally in the 19th century, but it sounds very strange today.)
The title of my question is a Russian proverb, for which I cannot think of an analog. All the examples I have seen on this website refer to actions rather than specifically speech. Can anyone give ...
The use of seem to is usually a hedge, or a softener. The examples above are suggesting that the person feels they should be able to do something but cannot find the right way to do it successfully. The same person wouldn't say, "I can't seem to speak Korean" because they have no reasonable expectation that they should be able to speak Korean.
Stick with cannot. Can't tends to be informal, and can not is usually considered a typo.
Generally, people use can't in speech and informal writing, and cannot or can not in formal writing or very formal speech. Also (as @Kris points out in a comment), cannot might be used when you need to carefully distinguish it from can't in speech.