Question

mathematics ---- my favourite subject when I was in high school​

Answer 1

Mathematics was my favorite subject when I was in high school​.

Explanation:

• As we can see the last part of the sentences shows that this is past tense.
• We could have added "is" in the given sentence but since it is a past tense we will use "was".
• Was is a verb used in past tenses to depict that the activity happened was happened in the past not present.
• The plural form of was is were.

Answer 2

Answer:

Mathematics was my favourite subject when I was in high school.

Additional information:

Past tenses:

✭ There are few words which makes the sentence past tenses, such as "before, had done", have eaten", "yesterday", "already".

Present tenses:

✭ The words which defines about the things which is done now and there are many other sub-tenses, such as "playing", "eating", "talking", "typing".

Future tenses:

✭ There are few words which describes about the future and also the examples are "will", "maybe", "will be/maybe", "Maybe I go to picnic next week", "I will be learning at 12th next year".