一次能源是指可以从自然界直接获取的能源，下列属于一次能源的是()。

In the passage "human problems" or "world problems" refers mainly to ______.

A．global food shortage

B．resources depletion

C．environmental pollution

D．all of the above

The passage uses the term "vegetative forms" to refer to ______.

A．Plants that infest human habitations

B．the fact that bacteria are really vegetables

C．the growing stage of the bacteria as opposed to the dormant stage

D．the difficulty in classifying the types of bacteria

The passage uses the term "vegetative forms" to refer to ______.

A．plants that infest human habitations

B．the fact that bacteria are really vegetables

C．the growing stage of the bacteria as opposed to the dormant stage

D．the difficulty in classifying the . types of bacteria

The passage uses the term "vegetative forms" to refer to ______.

A．plants that infest human habitations

B．the feet that bacteria are really vegetables

C．the growing stage of the bacteria as opposed to the dormant stage

D．the difficulty in classifying the types of bacteria

The whole passage implies that ________

A．only human beings have problem-solving intelligence

B．a person' s memory is different from a computer' s in every respect

C．animals are able to solve only very simple problems

D．animals solve problems by instincts rather than intelligence

The whole passage implies that______.

A．only human beings have problem-solving intelligence

B．a person's memory is different from a computer's in every respect

C．animals are able to solve only very simple problems

D．animals solve problems by instincts rather than intelligence

The whole passage implies that ______.

A．only human beings have problem-solving intelligence

B．a person's memory is different from a computer's in every respect

C．animals are able to solve only very simple problems

D．animals solve problems by instincts rather than intelligence

The passage is mainly about ______.

A．the composition of environment

B．the impact of environment on human

C．the impact of human on environment

D．the causes of environmental problems

A．a waste of human and natural resources

B．economic dominate over the competitors

C．constant creation of social problems

D．formation of a ever complex society

The whole passage implies that__________.

A.only human beings have problem-solving intelligence

B.a person's memory is different from a computer's in every respect

C.animals are able to solve only very simple problems

D.animals solve problems by instincts rather than intelligence