It is an astonishing fact that there are laws of nature, rules that summarize conveniently

-【21】qualitatively but quantitatively - how the world works. We might【22】a universe in which there are no such laws, in which the 108 elementary particles that【23】a universe like our own behave with utter and uncompromising abandon. To understand such a universe we would need a brain【24】as massive as the universe. It seems【25】that such a universe could have life and intelligence, because being and brains【26】some degree of internal stability and order. But【27】in a much more random universe there were such beings with an intelligence much【28】than our own, there could not be much knowledge, passion or joy.

【29】for us, we live in a universe that has at least important parts that are knowable. Our common-sense experience and our evolutionary history have【30】us to understand something of the workaday world. When we go into other realms, however, common sense and ordinary intuition【31】highly unreliable guides. It is stunning that as we go close to the speed of light our mass【32】indefinitely, we shrink toward zero thickness【33】the direction of motion, and time for us comes as near to stopping as we would like. Many people think that this is silly, and every week【34】I get a letter from someone who complains to me about it. But it is virtually certain consequence not just of experiment but also of Albert Einstein's【35】analysis of space and time called the Special Theory of Relativity. It does not matter that these effects seem unreasonable to us. We are not【36】the habit of traveling close to the speed of light. The testimony of our common sense is suspect at high velocities.

The idea that the world places restrictions on【37】humans might do is frustrating. Why shouldn't we be able to have intermediate rotational positions？ Why can't we【38】faster than the speed of light？ But【39】we can tell, this is the way the universe is constructed. Such prohibitions not only【40】us toward a little humility; they also make the world more knowable.

(1)

A．just

B．very

C．just not

D．not just