You are a made man.
君は成功間違いなしだ
You are going to save us an awful lot of time and trouble.
あなたのおかげでかなりの時間と手間が省ける
You can [can't] imagine what a terrible week I had.
本当にひどい1週間だったのだから(◆強調)
You can take my word for it.
間違いない
You must get up at 5 a.m. so as to catch the first train.
一番列車に間に合うように午前5時に起きなくてはいけません
You need a large block of time to collect your data.
データを集めるのにまとまった時間が必要だ
You should report on your progress in two weeks.
2週間の進捗しんちょくを報告しなさい
You'd better believe it.
〔間投詞的に〕((略式))本当に,疑いなく,きっと
You'll be here on time, I trust.
時間どおりに来てくれるよね
You're in.
((略式))おまえは仲間だ;親切ありがとうよ