【单选题】Advertisements are only read by a small group of people of high social status.
【单选题】Sociologists have long recognized that social tensions are______elements of group life.
【判断题】氮循环主要包括固氮作用、同化作用、氨化作用、硝化作用和反硝化作用。
【单选题】The neuroimaging studies show that shyness is______.
A.
a kind of disability due to differences on the brain
B.
something that only emerges in a child in infancy
C.
something that stays with the person for all his or her life
D.
not a learned behaviour—it is innate
【简答题】请写出硝化过程和反硝化过程的反应式,并比较硝化作用和反硝化作用的异同。