Tính nhanh:

12345 x 17 + 23 x 12345 + 12345 + 12345 x 35 + 12345 x 24

Mark the letter A, B, C or D to indicate the correct answer to each of the following questions.

Question 16: I came on Monday at ten o'clock ________ the morning.

A. at

B. on

C. in

D. under