BOB WROTE SOME LETTERS AND THEN WENT TO BED.A. AFTER BOB HAD GONE...

39. - DE KIEM TRA 1 TIET LAN 1
DE KIEM TRA 1 TIET LAN 1
39. Bob wrote some letters and then went to bed.A. After Bob had gone to bed, he wrote some letters.B. After Bob had written some letters, he went to bed.C. Before Bob wrote some letters, he had gone to bed.D. While Bob was writing some letters, he went to bed.