Everybody came to the party early enough, didn't they ? (were)
=> Everybody wasn't early enough to the party, were they ?
=> Everybody was earlyenough to the party, weren't they ?
Everybody chia theo số ít => was
* Nếu trong câu hỏi đuôi CN là everybody=> dùng they
Câu hỏi đuôi trước KD<=> sau PD