Arctangent
反正切
🗣️ 情景例句
Thank you. In there?
谢谢 。在那里面吗？
He hasn't answered my letter yet.
他还没有给我回信。
Old women in black shawls peered at us from doorways.
披黑纱巾的老妇人站在门口偷偷地瞅着我们。