A、Until he eats it. B、At least thirty minutes. C、All day. D、No more than thirty minutes. D细节判断题。考查学生抓住细节的能力，本题答案直到文章中部才出现：“Food

When you have a dog it is necessary to care for it very carefully. In return you will be loved by your dog as a kind monarch is by his people. The most important part of dog-care is cleanliness. Not only does the dog have to be kept clean. His environment should also be clean. The bed he sleeps in can be made with anything like a rug or a dog mattress, as long as it is kept clean.
    Proper feeding is also important to your dog’s health. Heavy aluminum feeding pans are best since they can not chip or break. A dog should be fed in the same place and on regular schedule. During feeding time it should be quiet. If your dog refuses to eat, don’t force him. Remove his food and don’ t feed him again until his next regular feeding.
    Food should never be left before a dog for more than thirty minutes under any circumstances. If he does not eat over a long period of time, your dog should be taken to veterinarian. Another important thing is to keep fresh water available to the dog during hot weather.
    One important thing that many dog owners forget is exercise for their dogs. Vigorous exercise helps build strength and keeps the dog healthy. Without it the dog development is impeded. A regular walk at a fixed time of the day is enough to help a smaller dog live a healthier and happier life. Large dogs, though, require a run in an open field.
    There are other things that are also important for a dog’s health - fixings like bathing, care of the teeth and nails, keeping them away from insects as much as possible. It’ s also necessary to provide special care while travelling. But ff you observe the three main points covered above, your dog will give you a great amount of pleasure.