Definition
The definition you referred to is Oxford Learners Dictionaries: congratulation: "1 congratulations [plural] a message congratulating somebody (= saying that you are happy about their good luck or success)."
"Congratulations" comes after the success is achieved, and you are saying that you observed their success or good luck and approve of it.
"Good luck" must come before their success - you are saying you hope they will succeed.
Congratulations and good luck!
You could congratulate someone for taking a prestigious exam, such as a bar exam, especially if the person was expressing a positive sentiment at the fact that they had finally reached this point:
Jane: "Hey Joe, guess what!"
Joe: "What!"
Jane: "I'm almost finished! Tomorrow I'm sitting for the bar exam!"
Joe: "Congratulations!"
(You might also say "Congratulations! And good luck!")
"Taking an exam" vs. "doing an exam"
While "I'm taking an exam" is much more common, there are other phrases that are acceptable or even preferred within certain dialects of English. Note the following Google N-Gram:
Google N-Gram: do an exam,doing an exam,take an exam,taking an exam,sit an exam,sitting an exam,sit for an exam,sitting for an exam,have an exam,having an exam,got an exam
Some of these results have a different context, such as a doctor who says, "I'm doing an exam" is performing an exam on someone. However, there are instances of "doing an exam" referring to the same meaning as "taking an exam" within the exact same idiomatic scenario. (There are also some subtle cases in different scenarios that could influence usage.) It would be conservative to use the phrase "I'm taking an exam" unless the culture you're in uses a different idiomatic phrase.
Credit to @Adam and other commenters for ideas and content of this answer.
Beautiful question!It states some people have all the luck while others are perpetually unlucky.In other words according to this somehow funny quote it is possible not to work hard and yet become luckier.In fact talks about people who describe themselves as lucky.They can achieve everything without trying.Even their failure is a success.
However, in my view,we all know that actually it's their outlook towards things that helps them create the circumstances for luck and their attitude helps them take advantage of it.Luck, it seems, isn't just luck. Instead, it's having a mindset of opportunity.
"Only move on so much the faster":Progress even faster than before
Best Answer
Your example sentence is correct and makes correct use of both bad luck and unlucky
Luck is:
Lucky is:
(Unlucky being the opposite of lucky)
Importantly, luck itself is a noun and can be either good or bad. That is, you can either have good luck (and therefore be lucky) or have bad luck (and be unlucky).
Note that, in general - if somebody is considered to have "a lot of luck", the implication is that they had a lot of good luck.