a field of wheat的用法和样例：
- They are reaping a field of wheat.
- We soon saw a field of wheat undulating in the breeze.
- We soon see a field of wheat undulate in the breeze.
- The willows over all the fen rippled and whitened like a field of wheat.
- The peasants are reaping a field of barley.
- The valley of the river was very fertile, and the young tender grass covered it like a field of wheat in May.