Question

るあ

ここの空欄の問題（3）、なぜsinceになるのですか、？

<Since と for の使い分け〉次の英文の空所に since か for のうち適する語を書きなさ
10 They have been in Sendai
iace
fore
Tom and I have been good friends tn
yesterday. inler a99d '
a week. こA間)
CR We have had no rain
we were children.
の Jack has wanted a computer
2ince
last month.