流动性较好的合金，能防止铸件浇不足、冷隔等缺陷，能获得轮廓清晰的铸件。
参考答案：对
Going to school _____ breakfast is bad _____ your health.[ ]
A. with; for
B. without; for
C. with; at
D. without; at
简述产品多样化策略的种类。
