听力原文： [14] If there are no more questions about the textbooks or syllabus, I'd like to

briefly explain the grading procedure I'll be using in this course. 50% of your grade will be based on the midterm examination and the final exam. Both of these exams will be given during class time and each will be 2 hours long. [15] In a lecture class this size, it is impractical and almost impossible to give make-up exams, so plan on being healthy and in class on those days; otherwise, your final grade average may suffer. The semester is 16 weeks long and quizzes will be given every 2 weeks to make sure you're keeping up with what's going on in class. [16] Quizzes will count as 15% of your grade and daily homework will count another 15%. Homework will be collected and graded by the teaching assistants in your laboratory sessions. [16] So, 50% for exams, 15% for quizzes, and 15% for homework. The remaining 20% of your grade will be based on class participation. I'm obviously not in a position to judge this, but I will be asking our teaching assistants to evaluate how actively you participate in their clasps. Remember, [17] the purpose of the laboratory sessions is to give you a chance to ask questions about the lecture and to discuss difficult points.

This talk most likely happens

A．during registration.

B．on the first day of class.

C．at midsemester.

D．during finals week.