The power of words
English is a tricky language. You cannot mix up tenses. For example, I walk to the store and bought butter. Here you find a confused mix of the present and past tense. Another problem is the use of prepositions. Take a look at this sentence: Don’t mention about it. What’s wrong here?
Similarly there are a number of pitfalls that you must look out for when you wish to construct a grammatically correct sentence.
Now, try your hand at this exercise and see how good your grammar is.