Arccos
反余弦
🗣️ 情景例句
I know he will love the new photographs for your book.
我相信他会喜欢你为你的书所拍的这些新照片。
What's the rush?
你急什么？
The whole village has been working day and night gathering and threshing this year's crop before the September rains.
全村的人都日夜奋战，要赶在9月的雨季之前把今年的庄稼收获上来，打完场。