What is the end result?
Ask a question and, as an added bonus, you will get a free gift.
What do you think is wrong with this sentence?
To ask is to pose a question, so question is redundant. A bonus is an extra feature, so to say added is unnecessary. And, finally, if you had to pay for something it is not a gift.
In our conversations, we often use phrases like this. Can you complete the phrases in these cards?