Answers
答えは
(1) They have practiced judo since
last once.
(2)Has Yuki In that room for an hour?
(3)How long have you taken care of the cat?
ですね。
現在完了は
主語+have(has)+いつから、どれくらいの間
という決まりがあります。
これさえ抑えれば現在完了はすごく簡単な
単元です。
Were you able to resolve your confusion?
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訂正
(1)once× month○
(2)Yukiの後にbeen