解决各目标之间的矛盾性靠（）这一概念来解决。
参考答案：权
厨房培训的注意事项有哪些？
— How do you find air conditioners made by Haier Group Corporation?
— Of high quality. We ______ their products all these years. [ ]
A. sell
B. have sold
C. have been sold
D. have been selling
