Past Tense
noun
The past shape is how things were in the past. To describe those things (like you would with an adjective, aka 形容詞), you'd use past tense.
かこけい
This is a jukugo word, which usually means on'yomi readings from the kanji. If you know the readings of your kanji you'll know how to read this as well.
この場合は過去形は使わないんですか？
Don’t you use the past tense in this case?