（）是工业生产配合饲料的必要前提和遵循依据。
参考答案：饲料配方
Prices of the basic necessities of life have been going up sharply since word came that war would
________between the two countries soon.[ ]
A. watch out
B. break out
C. die out
D. give out
从双口网络（）看进去的阻抗，称为输入阻抗Zin＝。
。