Catholic schools in Perth，Australia，which have been testing them since October 2013，have seen similar results.Grove House Primary School in Bradford，West Yorkshire，became Europe's first test one，with a seven﹣week trial that involved the use of desks made by Ergotron in their fifth﹣grade classrooms．While official results are not out yet，early reactions from both teachers and students，have been extremely encouraging．

The findings of these studies and others done previously，all seem to mean that allowing kids to move around in classrooms is a win﹣win for students and teachers﹣it helps kids get healthier and provides educators with a more engaged audience．

28．According to the first paragraph，what may make the students at school unhappy is that　 　．

A．they have to exchange desks with each other

B．they have to exchange traditional desks for ones with no seats

C．there are no seats for them to sit in class

D．the officials show no sympathy to them at all

29．According to the teachers，older students may not like stand﹣up desks because　 　．

A．they are cleverer than younger students

B．they are easily tired of standing long

C．they have formed the habit of sitting

D．they do badly in class while standing

30．What is most likely to be the result of the seven﹣week trial?　 　

A．The standing desks can't be used at all．

B．It is good for students to use stand﹣up desks．

C．More tests should be done in other schools．

D．The students are different in personality．

31．Why do the teachers like the standing desks?　 　

A．Because the educators can draw the students'attention．

B．Because the teachers can keep the students healthy．

C．Because the students can have a walk in the classroom．

D．Because the standing desks can keep the students concentrated．

　D

If you ask most people what water tastes like, they'll probably tell you that water has no taste and they may give you a funny look. But if you were a fruit fly, asking another fruit fly, that question might have a different answer.

To a fruit fly, water has a taste. Scientists want to know how the fruit fly knows water because this information may help in learning how other animals - or even individual cells - manage to use water in the right way. Water is vital to life, but too much or too little can be deadly to a living creature. So by understanding how the fruit fly tastes water, researchers may learn more about other living things.

According to the new study, a protein called PPK28 makes it possible for a fly to taste water. Proteins build cells and tissues, fight disease and carry messages between cells. It's not surprising that a protein is responsible for the fruit fly's