Advanced Past Tenses: Mastering Past Perfect, Past Continuous, and Past Perfect Continuous

Quá khứ hoàn thành (Past Perfect): had + past participle
Phủ định: had not (hadn't) + past participle
Nghi vấn: Had + subject + past participle?
Quá khứ tiếp diễn (Past Continuous): was/were + verb-ing
Phủ định: was/were not (wasn't/weren't) + verb-ing
Nghi vấn: Was/Were + subject + verb-ing?
Quá khứ hoàn thành tiếp diễn (Past Perfect Continuous): had been + verb-ing
Phủ định: had not been + verb-ing
Nghi vấn: Had + subject + been + verb-ing?