【单选题】请听录音，选择划线部分的语调。He turned off thelight( ), took hisbag( ), opened thedoor( ) and went out. A: ↗ ↗ ↗ B: ↘↘↘

已知描述系统的差分方程为  [tex=9.571x1.286]efHFWAkWPqkNoYR5t8JvYQSQsdQd6t+QJFLwA3X9GgU=[/tex]  。若 [tex=4.071x1.286]kxu13uRWLUxdPEg/hiSBAg==[/tex] , 求系统的零输入响应 [tex=2.286x1.286]gY0kNII373bLll5Vrmxb6A==[/tex].