I know I (14. not write) to you before, but I (15. be) so busy recently that I (16. not have) time for
Giải thích
14. shouldn’t/ oughtn’t have written
15. have been16. haven’t had17. should/would have telephoned18. have forgot(ten)
14. shouldn’t/ oughtn’t have written
15. have been16. haven’t had17. should/would have telephoned18. have forgot(ten)