a sack of sugar的用法和样例：
- Now, as to vegetable, give me a sack of potato.
- He hiked up a sack of grain on his shoulder.
- The poor thing has a figure like a sack of potatoes.
- There is a sack of potatoes at the corner of the room.
- The burglar carry a sack of clock from the shop.
- There was a sack of corn in the corner of the barn.