题干

用甲、乙两种原料配制成某种饮料,已知这两种原料的维生素C含量及购买这两种原料的价格如下表:


甲种原料

乙种原料

维生素C含量(单位•千克)

600

100

原料价格(元•千克)

8

4

现配制这种饮料10kg,要求至少含有4200单位的维生素C,若所需甲种原料的质量为x kg,则x应满足的不等式为(   )

A:600x+100(10﹣x)≥4200

B:8x+4(100﹣x)≤4200

C:600x+100(10﹣x)≤4200

D:8x+4(100﹣x)≥4200

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答案(点此获取答案解析)

A

同类题5

阅读下列短文,从每题所给的A、B、C和D四个选项中,选出最佳选项。

D

    Adults understand what it feels like to be flooded with objects. Why do we often assume that more is more when it comes to kids and their belongings? The good news is that I can help my own kids learn earlier than I did how to live more with less.

    I found the pre-holidays a good time to encourage young children to donate less-used things, and it worked. Because of our efforts, our daughter Georgia did decide to donate a large bag of toys to a little girl whose mother was unable to pay for her holiday due to illness. She chose to sell a few larger objects that were less often used when we promised to put the money into her school fund(基金)(our kindergarten daughter is serious about becoming a doctor)

    For weeks, I've been thinking of bigger, deeper questions: How do we make it a habit for them? And how do we train ourselves to help them live with, need, and use less? Yesterday, I sat with my son, Shepherd, determined to test my own theory on this. I decided to play with him with only one toy for as long as it would keep his interest. I expected that one toy would keep his attention for about five minutes, ten minutes, max. I chose a red rubber ball-simple, universally available. We passed it, he tried to put it in his mouth, he tried bouncing it, rolling it, sitting on it, throwing it. It was totally, completely enough for him. Before I knew it an hour had passed and it was time to move on to lunch.

    We both became absorbed in the simplicity of playing together. He had my full attention and I had his. My little experiment to find joy in a single object worked for both of us.