d

If the note of D is sounded on a harp, all the corresponding D strings of other octaves will likewise resonate.

如果用竖琴演奏D音符，其他八度音阶所有相应的D弦都将发出共鸣。

In figure 24 'D' denotes quantity demanded and 'S' denotes quantity supplied.

在图24中，D代表需求量而S代表供应量。

Butter, margarine, and oily fish are all good sources of vitamin D.

黄油、人造黄油和多脂鱼都含有丰富的维生素D。

This special form of vitamin D is naturally present in breast milk.

这种特殊形态的维生素D天然存在于母乳中。

Milk, oily fish and egg all contain vitamin D.

牛奶、油性鱼类和鸡蛋都含有维生素D.

Decide whether the ball is in square A, B, C, or D, then call and leave your answer

选定球放在A、B、C、D哪个方格，然后打电话来，留下您的答案。

The second quotation is from an essay that D H Lawrence wrote in the nineteen-twenties.

第二段引文出自D.H.劳伦斯20世纪20年代写的一篇文章。

She went from a D in her mocks to a B in the real thing.

她模拟考试得了D，到了真正考试的时候却拿了个B。

Two percent of total sales is spent on R and D.

总销售额的百分之二的花费在研究开发上.

Kevin: Yes, I've started, and I've found some good people for R and D.

凯文: 是的, 已经开始了, 而且我也找到了几个不错的研发人员.

This kind of lighting encourages vitamin D synthesis in the skin.

这种光照会促进皮肤中维生素D的合成。