Past tense is used to express the activities in the past.
You have to change the verbs into Verb 2 in positive sentence whenever it is verbal sentences. in other hand you have to change to be ( am, is or are ) into was or were whenever it is nominal sentence.
A. Verbal sentence
(+) Yesterday, Paul and John went fishing.
(+) We visited uncle Jeff last week.
(+) I saw Mr. Parmana two days ago.
if you want to make them into negative sentences, please add did not after subject and change the verb into bare infinitive.
(-) Yesterday, Paul and John did not go fishing.
(-) We did not visit uncle Jeff last week.
(-) I did not see Mr. Parmana two days ago.
You can change them into interrogative sentences by placing did in the beginning of the sentences and keep the verb in infinitive form;
(?) Did Paul and John go fishing?
(?) Did you visit uncle Jeff last week?
(?) Did you see Mr. Parmana two days ago?
B. Nominal Sentence
When you find nominal sentences, you have to change to be into was or were. it depends on what the subject is. Was is used for I, He, She and It but were is used for you, we and they.
(+) I was late yesterday.
(+) We were happy during the party last night.
(+) She was absent last week.
we can change them into negative sentences by adding not after was and were.
(-) I was not late yesterday.
(-) We were not happy during the party last night.
(-) She was not absent last week.
if you want to make interrogative sentences, you just put the to be in the beginning of your sentences :
(?) Were you late yesterday?
(?) Were you happy during the party last night?
(?) Was she absent last week?
C. Time signals
last week, yesterday, ...ago. just now etc...
