a 50 seat cinema为什么seat不加s

here's a seat for you.为什么不用yourself. seat It's still polite to give up your seat to an old man 里为什么要加a Here's a seat .Please___this one,Mary? There's only one seat left 和 Is any cola left 中的 left 为什么要加 That's my().Please () here. A.seat,sit B.sit,sit C.sit,seat a seat belt "have a seat Have a seat,please. have a seat 是什么 take a seat ,please. Have a seat,please