Isovel
等速线, 等速度曲线
🗣️ 情景例句
Who has torn these pages out of the book?
谁撕掉书上的这几页？
How many boxes are you going to use?
你要用几盒？
Only very thrifty children manage to fill up a money box.
但是能把储蓄罐装满的只有屈指可数的几个特别节俭的孩子。