A 15-year, 100, 6%, semi-annual coupon and a yield rate of 6% (nominal annual interest rate) issued on April 1, 2010 and due on April 1, 2025. Smith purchased the bond on January 1, 2020.

2. Smith purchased the bond on January 1, 2020, and received four coupons in 2020. The bond will then be sold on December 31, 2020 at a price of 120. According to the transaction situation in 2020, find time t0=0, t1, t2, t3=1,and in each time cash in and cash out