阅读下面短文，按照句子结构的语法性和上下文连贯的要求，在空格处填入一个适当的词或使用括号中词语的正确形式填空。

Recently it has been observed that more and more people are switching to organic vegetables and fruits. They are 小题1:(nature) and safe for the human body to consume. Organic farming __小题2:(increase) and evolved in a large way due to this large demand by now. Farmers are getting better at the art of growing organic vegetables and there are many helpful tips 小题3:__ they share with other members of the organic farming circle. 小题4:you are a gardener and interested in growing organic vegetables, 小题5:is wise to be aware of these tips and choose the best organic garden tip that helps 小题6:garden to produce healthy and better vegetables.

One helpful organic garden tip that works well for all farmers is 小题7:(make) your own fertilizer. This is 小题8:kind of fertilizer made of dry leaves, fruit peelings and kitchen food disposables. These materials are buried underground and kept there 小题9:some time. With fermentation（发酵）taking place the soil becomes richer with nutrients. This means you get a fertilizer that does not have chemicals at all. This fertilizer enhances the soil and so the vegetables and fruits are 小题10:(health) and better.

把一面镜子斜着插人水盆中,放在阳光下，在天花板上就可以看到彩色光带，对这个现象,下列说中正确的是    （   )

A．这是光的全反射现象

B．这是光的色散现象，起到棱镜作用的是水

C．a是红光，d是紫光

D．在真空中“光束的传播速度大d光束的传播速度小