[填空题]Some plants are___________________________________________(对光线很敏感); they prefer the shade.

[单项选择]Nuclear power plants are some of the largest producers of （） wastes, with each plant producing barrels of radioactive material that must be stored in special protective containers.
A. biodegradable
B. hazardous
C. reasonable
D. durable

[简答题]Some was collected by this season’ s plants as carbon compounds. Some was stored by plants and trees ages ago. (Passage 3 )

[单项选择]Some plants are very _________ to light; they prefer the shade.
A. sensible
B. flexible
C. objective
D. sensitive

[单项选择]Some plants are very __________ to light; they prefer the shade.
A. sensible
B. flexible
C. objective
D. sensitive

[填空题]Some plants are __________ (对光线很敏感); they prefer the shade.

[填空题]Some plants ________________ (对污染很敏感) that they can only survive in a perfectly clean environment.

[单项选择]

Plants in Desert
Only special plants can survive the terrible climate of a desert, for these are regions when the annual range of the soil temperature can be over 75℃. Furthermore, during the summer there are few clouds in the sky to protect plans from the sun’ s ray. Another problem is the fact that there are frequently strong winds that drive small, sharp particles of sand into the plants,earing and damaging them. The most difficult probiem for all forms of plant life, however, is the fact that the entire annual rainfall occurs during a few days or weeks in spring.
Grasses and flowers in desert survive from one year to the next by existing through the long, hot, dry season in the form of seeds. These seeds remain inactive unless the fight amount of’rain falls. If no rain falls, or if insufficient rain falls, they wait until the next year, or even still the next. Another factor that helps these plants to survive is the fact that their life cycl
A. Right
B. Wrong
C. Not mentioned

[单项选择]
Plants, like animals, are subject to diseases of various kinds. It has been estimated that some 30,000 different diseases attack our economic plants; forty are known to attack corn, and about as many attack wheat. The results of unchecked plant disease are all too obvious m countries which have marginal food supplies. The problem will soon be more widespread as the population of the world increases at its frightening rate. Even in countries which are now amply fed by their agricultural products there could soon be critical food shortages. It is easy to imagine the consequences of some disastrous attack on one of the major crops; the resulting famines could kill millions of people, and the resulting hardship on other millions could cause political upheavals disastrous to the order of the world.
Some plants have relative immunity to a great many diseases, while others have a susceptibility to them. The t
A. Some plant diseases may be caused by bacteria.
B. Some plant diseases may be caused by pathogens.
C. Some plant diseases may be caused by fungus.
D. Symptoms are always helpful in identifying diseases.