下面是一道SAT数学练习题，请自行完成后参看答案和解析。

　　Read the following SAT test question, then click on a button to select your answer.

　　There are n students in a biology class, and only 6 of them are seniors. If 7 juniors are added to the class, how many students in the class will not be seniors?

　　A.n – 3

　　B.n – 2

　　C.n – 1

　　D.n + 1

　　E.n + 2

答案及解析

　　Correct Answer: D

　　Here's Why:

　　At first, there are n students in the class, and 6 of them are seniors. It follows that initially n – 6 students are not seniors. If 7 juniors are added to the class, there will be n – 6 + 7, or n + 1, students in the class who are not seniors.

　　Difficulty: Medium

　　Question Type: Standard Multiple Choice