1 . Scientists have discovered how plants manage to live alongside each other in places that are dark and shady. Plants in the deep darkness of a thick forest, where natural supplies are not very great in amount, won’t attempt to top their neighbors in growth as those in moderate (中度的) shade do. In deep shade conditions, it would be a waste of energy and harmful to survival because green shoots would never be able to top their larger neighbors in growth.

So how do plants prevent such growth in deep shade conditions? The secret lies in the clocks insides them, say scientists from the John Ines Centre and the University of Bristol.

They have discovered that when plants notice deep shade, this changes the expression of genes parts of the circadian clock (昼夜节律时钟) — the inner daily timer found in plants and other things. These clock parts perform an additional role in preventing plants from lengthening and overtopping neighbors.

The work identifies a previously unknown role of the circadian clock in controlling plant development and the findings may have possible effects on both natural plant populations and crops. Professor Antony Dodd of the John Innes Centre said, “The biological clock of plants plays a big part in their development and fitness. This work casts new light on a new role of the circadian clock in adapting plants to competition with other plants in their environments.” “It also gives us new insights into how plants adapt to very deep shade, where resources are very limited,” said Professor Kerry Franklin at the University of Bristol.

This work provides evidence for the firmness of the circadian clock in stressful environments, and information that may be useful in developing new generations of crops in a challenging climate.

1. What do plants normally do in moderate shade?

A．Struggle to preserve energy.	B．Compete for limited resources.
C．Try to outgrow their neighbors.	D．Depend on each other to survive.

2. How does the circadian clock affect plants?

A．By changing their gene expression.	B．By making them realize light change.
C．By helping them adapt to the darkness.	D．By controlling their growth in deep shade.

3. Why does the author write the text?

A．To share a new discovery about plants.	B．To introduce the role of the circadian clock.
C．To explain plants secret of living in forests.	D．To compare plants living in certain condition.

4. What is the best title for the text?

A．How plants face a challenging climate

B．Why plants respond to different shade levels

C．Why the circadian clock is vital to plants' growth

D．How plants become good neighbors in times of stress

2 . 阅读下面短文，在空白处填入1个适当的单词或括号内单词的正确形式。

Yuan Longping, Father of Hybrid Rice,     1     passed away on Saturday at 91, will be long remembered as one of the most honorable leaders, the World Food Prize Foundation said.

Yuan was a co-winner of the 2004 World Food Prize, the top international honor recognizing the deeds of     2     (individual) who have advanced human development by     3     (improve) the quality, quantity and availability of food in the world. Yuan shared it with Monty Jones, an African rice breeder.

Yuan’s pioneering research has     4     (complete) helped transform China from food shortage to food security within three decades, according to an earlier statement     5    (release) by the WFP.

Barbara Stinson, president of the WFP Foundation, said Yuan was credited not only for hybrid rice, but also for the ability     6    (change) land out of rice production and into other kinds of food production, including fish ponds, other fruits and vegetables, increasing the nutritional content of food in China, and contributing     7     the reduction of hunger and poverty as well.

Yuan started hybrid rice research in 1964 and     8    (succeed) in developing the world’s first high-yield hybrid rice strain in 1973. So far, its annual growth area     9    (reach) 8 million hectares (公顷)in countries including India, Bangladesh, Vietnam) Brazil and the US.

“He’s made such     10     powerful contribution. Professor Yuan will be long remembered. ” Stinson told China Daily.