kalau gabungan simple past sama past continuous kalimat negative dan interrogative kaya gimana ?

kalimat utamanya yang dijadikan negative dan interogative.

contoh:
The accident happened while they were waiting for the bus.
(-) The accident didn't happen while they were waiting for the bus.
(?) Did the accident happen while they were waiting for the bus?

I was studying when you called.
(-) I wasn't studying when you called.
(?) Was I studying when you called?