Student or Learner
Do you say think hard?
e.g. I thought really hard to solve the question, but I couldn't.
If hard doesn't fit, what adverbs go with think?
Hard is a basic word, but I think it's hard to use it correctly.
This is in fact a common English collocation, which is sometimes used as part of a longer phrase" Think long and hard". "Think deeply" is another possible combination.