When taking a written test, you can generally eliminate D answers on a multiple choice question that are exactly the same as A, B or C except for a differing preposition (e.g. in, on, at, from, of, during)

For example, if you have an English question like<br><br>Which of the following sentences is grammatically correct?<br><br>A: I am going to the beach on Saturday<br>B: I am going to the beach during Saturday<br>C: I am going to the beach from Saturday<br>D: I am going to the beach in Saturday<br><br>No real sentence that is grammatically correct, in English, is like D. <br><br>And certainly, no sentence that you have learned in school, which is what these tests are based off of, is like D. <br><br>I've never encountered any big exceptions to this rule on a written test.