请选择DCBA3q0A/j*L-h5a -Alison, how long have you been skating? - I have been skating ________ nine o'clock.4r9N1}5L0{0l.d0n-k;r,i2V.S-M5`+K-y
A. for4r9N1}5L0{0l.d0n-k;r,i2V.S-M5`+K-y
B. at4r9N1}5L0{0l.d0n-k;r,i2V.S-M5`+K-y
C. since4r9N1}5L0{0l.d0n-k;r,i2V.S-M5`+K-y
D. from4r9N1}5L0{0l.d0n-k;r,i2V.S-M5`+K-y