think of sb/sth
phr. v..phr. v.. To have an opinion about someone or something, or to bring an idea or memory into your mind.
phr. v.. To hold an opinion about a subject, or to recall or conceive of an idea or memory; a transitive phrasal verb.
What do you think of this new song?
I can't think of his name right now, but I remember his face perfectly.
It is sobering to think of the immense challenges future generations will face as a result of climate change.
Use 'think of' for opinions and quick thoughts, and 'think about' for deeper consideration.
Contrast 'think of' (opinion/recall) with 'think about' (deeper consideration); 'What do you think of the idea?' vs. 'I need to think about the idea.'
I can't think the answer.I can't think of the answer.The preposition 'of' is required to connect the verb 'think' to the object of your thought.