a piece of toast的用法和样例：
- He was choking on a piece of toast.
- Lally was spreading marmalade on a piece of toast.
- Lally was spreading marmalade on a piece of toast .
- I need a piece of string to tie this parcel up.
- Susan helped herself with a piece of toast and spread it with. A red sky at night indicates fine weather the following day.
- She was hit by a piece of falling masonry.