a high crop yield的用法和样例：
- These trees gave a high yield of fruit this year.
- In Iowa, that region is the north-western part of the state, which enjoys high crop yields but gets 25-50 cents less per bushel because it is too far from the Mississippi river barges.
- One of those ways, associated with higher crop yields, is to be sure that limitations of some other nutrient do not detrimentally affect N uptake and use.
- The medieval town was fortified with a high wall and a deep moat.