A、At dawn. B、In the morning. C、At noon. D、In the evening. B录音中提到应该在上午给玫瑰浇水，所以选项B正确。

Most kinds of rose plants come from Asia. But roses are also native to other areas including northwest Africa, Europe and the United States.(5)In 1986, the U. S. Congress chose the rose as America’s national flower. Technically, Congress and President Ronald Reagan declared it the " national floral emblem". Whatever the name, the decision did not smell sweet to lovers of other flowers. Some people say roses are difficult to grow. But you have a good chance of success if you start with a few suggestions from experts.(6)You should plant your roses where they can get sunshine for about six hours on bright days. You can buy roses from a garden center or by mail order. You can buy potted roses, also known as container roses, or bare-root plants. Each kind has its fans. When growing roses, the soil should feel moist deep down.(7)Watering should be done in the morning. That can prevent problems called black spot and mildew. But do not water too much. Jeffrey Dinslage says people often ask him about unhealthy discoloration on rose leaves. Me says the spots are usually caused by too much water. After heavy rains or too much watering, he advises pulling away mulch temporarily from around the roots. This will help dry the soil.
5. When was rose chosen as the national Mower of America?
6. How many hours of sunshine do roses need on bright days?
7. When should rose plants be watered?