5.Scientists found the FKF1 protein when they were 　　　.

A.answering a question

B.controlling the colors of flowers

C.planting flowers in the garden

D.studying a plant called Arabidopsis

答案:D

解析:根据第三段中的"Researchers found the FKF1 protein when they were studying a plant called Arabidopsis(拟南芥)."可知选D项。

6.The best time for flowers to come out is when 　　　.

A.it rains in spring　

B.there is light in the late afternoon

C.it is getting dark　

D.the sun goes down early

答案:B

解析:根据第四段中的"Plants produce this protein every day in the late afternoon all year."和"...the FKF1 protein can be made active by day light and the plants 'know' it is time to flower."可知,最好的开花时间是下午有光的时候。

7.Scientists believe that 　　　.

A.other plants also know when to flower

B.flowers are more valuable than fruit and vegetables

C.people have known how to control when flowers come out

D.if the weather is cold and days are short,plants will flower

答案:A

解析:根据倒数第二段中的"...they believe that it is the same with many other plants..."可知,科学家相信其他的植物也知道什么时候开花。

　　It was nearly dark and the sun was dropping down the mountains far away.Little Tom came back home,with tears in his eyes.

"What's the matter,Tom?How's your trip?" his mother asked with a big smile."I failed.The mountain is so high and full of big or small stones on the way and I still went ahead.But I was tired and it was so late that I had to come back." Tom cried."It doesn't matter.You are only 14 years old after all.You will have another chance." his mother said."But,standing at the top of the mountain is my dream!" Tom said.His father came over and asked,"Did you see the green trees on your way to the mountain?" "Sure,and there were a lot of beautiful flowers by the side of the road." Tom replied."Did you hear the birds singing?" his father asked."There were many kinds of birds singing in the trees,and the sound was very sweet." Tom said."Did you feel the beauty of nature?" his father asked."Yes,the blue sky,the white clouds,the green trees and the colorful flowers made a nice picture." Tom answered."That's enough!" his father smiled and said,"Please