You had better not be late tomorrow.
あすは遅刻してはいけない
You must not guess at the answers.
当て推量で答えてはいけない
You must not misbehave so.
そんな無作法をしてはいけない
You must take his stories with a grain of salt.
彼の話はまともに受け取ってはいけない
You mustn't sign the contract until you hear from me.
私から連絡のあるまで契約書に署名してはいけない
You need to set [put] your mind to your business.
仕事に全力を傾けなくてはいけない
You shouldn't hit children on the head.
子どもの頭をたたいてはいけない
“Do you have to go out now?” “I have to (go out now), and so have you (to go out).”
「もう出かけなくてはいけないの」「私はね．君もだろ」．
“You can't go to the dance.” “Why not?”
「ダンスパーティーに行ってはいけない」「どうして」
