A habitual action in the past that 'used to run' seems to indicate would be translated using the past imperfect tense as 'दौड़ती थीं' or 'दौड़ा करती थीं'.
Eg: मेरी माँ कल तक दौड़ती थीं - My mother used to run till yesterday
मेरी माँ पहले दौड़ती थीं - My mother used to run before
However, you wouldn't have a specific time like 'yesterday' when talking about habitual actions. What do you mean when you say 'used to run yesterday'?
Actually I also think “used to run yesterday” sounds weird and I don’t really know what I meant, but I just think that the transitions often are a bit odd and as I understood it before था (when it’s not the only verb) translated the sentence to ‘used to’.
Now, if the word कल was omitted, would it translate to “my mother used to be running”?
Or does था with रहा always translates as “was”?
था is the past tense form of होना which marks the past tense forms of other verbs (except the simple past tense which requires no auxiliary). These past tense forms are:
Past continuous tense: This is similar to the present continuous (मेरी माँ दौड़ रही हैं - 'My mother is running') and uses two auxiliary verbs- रहना and होना.
You just replace the है in the present continuous tense with था. The sentence in the past continuous is मेरी माँ दौड़ रही थीं' - 'My mother was running.
Past perfect tense: For this tense, you add a था to the simple past tense form. The simple past tense is मेरी माँ दौड़ीं - My mother ran. So, the past perfect is मेरी माँ दौड़ी थीं - My mother had run.
Note that if, instead of था, you had added a है, it would be the present perfect tense - मेरी माँ दौड़ी हैं - My mother has run.
(These tenses would require the subject to tack on a ने if the verb is transitive.
Eg: मेरी माँ ने खाया था - My mother had eaten)
Past imperfect tense: This tense is used to indicate habitual actions in the past.
English does not count it as a distinct tense and sometimes uses the simple past in its place like in 'On school nights we slept early'. At other times, we use 'used to' to specify that the action was habitual.
For this tense in Hindi, you replace the है in the simple present with था.
Since the simple present is मेरी माँ दौड़ती हैं -'My mother runs', the past imperfect would be 'मेरी माँ दौड़ती थीं' - 'My mother used to run'.
Past perfect continuous tense: You replace the है in the present perfect continuous tense with था. The present perfect continuous is मेरी माँ दौड़ती रही हैं - 'My mother has been running'. So, the past perfect continuous is मेरी माँ दौड़ती रही थीं - 'My mother had been running'.
Since it's often clear from the context (because you have durations) that the sentence is talking about the past, था is sometimes omitted from such sentences.
Also, just like the present continuous is used in Hindi in place of the present perfect continuous, the past continuous is often used in place of the past perfect continuous when there is no ambiguity.
For transitive verbs in the simple past tense, past perfect tense etc, the verb conjugates with the gender and the number of its objects. So, 'My mother had eaten a roti' would be 'मेरी माँ ने रोटी खाई थी' because रोटी is feminine singular, 'My mother had eaten apples' would be 'मेरी मां ने सेब खाए थे' because सेब is masculine plural etc. Since the verbs don't conjugate with the subject, we add ने to it so that it becomes an 'indirect' subject (this type of construction is known as 'ergative').
When there are no objects, the verb is masculine singular like in मेरी माँ ने खाया था.
Yes. The other sentence is quite weird. I would have taken it to be चार दिन पहले तक वह यहाँ खेलती थी। - She used to play here until four days ago.