Past Time Expressions

Time expressions indicate the tense.

Present Simple - Usually, never, generally, always, seldom, often, sometimes, every day/week/month/year
Present Continuous - At present, now, at the moment – listen, look (verbs)

Present Perfect - Already, just, yet, recently, lately, ever, never.

Present perfect or present perfect continuous tense - Since, for

Past Simple - Yesterday, last week, two hours ago
Past Continuous - at this time yesterday, at 4:30 yesterday, when he came, while he was reading.
Future Simple - Tomorrow, next week, next year
Future Progressive (Continuous) - at this time tomorrow

Past Perfect Simple:

by the time + past tense: By the time I got home, he had gone to sleep.

after/before + past tense: After I had eaten, I went to school.

Past Perfect Continuous:

for - since + when/before - something happened: I had been reading for an hour when he came.

when: When John got home, his brother had been surfing the web for five hours.