[填空题]
The human brain is the most complex structure in the universe.
It contains {{U}} (36) {{/U}} 100 billion nerve cells, each of which has
thousands of connections with each other. Their {{U}} (37) {{/U}}
controls each of the body’s functions, allows thoughts, perceptions, memories,
feelings, and also {{U}} (38) {{/U}} and communication. Understanding
just how the brain works, in health or in sickness, is one of the greatest
{{U}} (39) {{/U}} of our time. What is determined by genes, what is
formed by experience Scientists-are {{U}} (40) {{/U}} all aspects of
the nervous system. Great progress can be {{U}} (41) {{/U}} in
visualizing and modeling brain functions, as well as in research into their
biological basis. Today, it is {{U}} (42) {{/U}} that 30 to 50 percent of
human genes exercise their function chiefly in the brain. This gives an
{{U}} (43) {{/U}} of the complexity of the genetic control and
development. {{U}} (44) {{/U}}. Ha
