12．It happens every spring．Flowers come out everywhere on the same day．But how do plants"know"when to flower？
For years，it has been．difficult question for scientists．But a US research group may have finally answered it-the secret lies in a protein（蛋白質(zhì)）called FKF1．This helps plants to know when the days become long and when they get short．Then they can tell the seasons are changing．
Researchers found the FKF1protein when they were studying a plant called Arabidopsis．It is sensitive to sunlight，and can be made active by sunlight．
Plants produce this protein every day in the late afternoon all year．If there is no light at this time，for example in winter when the sun goes down early，the protein won't be active．But when spring comes and the days get longer，the FKF]protein can he made active by day light and the plants"know"it is time to flower．
"If there is light in the late afternoon，plants will know that the days are getting longer and that it is the best time for flowers to come out，"explained Takato Imaizumi，leader of study．But when conditions are poor for growing，such as during autumn or winter when the weather is cold and days are short，plants won't flower．
Although researchers have only studied how the FKF1protein works in the Arabidopsis，they believe
that it is the same with many other plants，including crops such as rice and wheat．This could be useful to the agricultural industry．
"1f we can control when flowers come out，we might be able to increase crop production．"lmaizumi said．
26．The passage is mainly aboutA
A．how plants"know"when to flower
R what people can do with plants
C．how seasons are changing
D．what kind of plant Arabidopsis is
27．Scientists found the FKFI protein when they wereD
A．planting Arabidopsis
B．controlling the colours of flowers
C．planting flowers in the garden
D．studying a plant called Arabidopsis
28．Which of the following is true according to the passage？A
A．Arabidopsis is sensitive to sunlight．
B．Flowers can tell the seasons are changing．
C．Scientists can control when flowers come out．
D．Scientists have studied the protein in rice．
29．The best time for flowers to come out is whenB．
A．it rains in spring
B．there is light in the late afternoon
C．it is getting dark
D．the sun goes down early
30．Scientists believe thatA
A．people have known how to control when flowers come out
B．flowers are more valuable than fruits and vegetables
C．other plants also know when to flower
D．if the weather is cold and days are short．plants will flower．
分析 植物的花每年春天開放，植物怎樣知道什么時候開花呢？原來植物體內(nèi)有一種叫FKF1的蛋白質(zhì)，幫助植物知道時間的變化和季節(jié)的輪回．本文從生物學(xué)的角度給我們講述了植物開花的秘密．
解答 26．A 推理判斷題．本文從生物學(xué)的角度給我們講述了植物開花的秘密．故選A，植物怎樣知道何時開花．
27．D 細節(jié)理解題．由第三段的第一句"Researchers foundthe FKF1 protein when they were studying a plant called Arabidopsis"可知科學(xué)家在研究一種叫Arabidopsi的植物時發(fā)現(xiàn)了FKF1蛋白質(zhì)，故選D．
28．A 細節(jié)理解題．根據(jù)Researchers found the FKF1protein when they were studying a plant called Arabidopsis．It is sensitive to sunlight可知Arabidopsis對陽光很敏感．故選A．
29．B 細節(jié)理解題．由第三段里的"If there is light in the late afternoon，plants will know that thedays are getting longer and that it is the best time for flowers to come out，"可知植物開花的最好時間是下午晚些時候有光線時，故選B．
30．A 推理判斷題．由第四段的第一句"Although researchers have only studied how the FKF1 protein works in the Arabidopsis，they believe that it is the same with many other plants"可知其它植物也知道何時開花，故選A．
點評 做題時首先要仔細閱讀短文，掌握大意，然后結(jié)合具體的題目，找出相關(guān)信息，就可以確定正確答案．
