2013高考英语（完形填空）倒计时冲刺50天（8）及答案
We have known for a long time that flowers of different plants open and close at different times of day.This is so __1__ that there seems to be no need to ask the reason for it.Yet no one __2__ understands why flowers open and close like this at particular times.The process is not as __3__ as we might think，as recent experiments have shown.In one study，flowers were kept in constant __4__.We might expect that the flowers，without any information about the time of day，did not open as they __5__ do.As a matter of fact，they __6__ to open at their usual time.This suggests that they have some mysterious（神秘的）way of knowing the __7__.Their sense of time does not __8__ information from the outside world；it is，so to speak，inside them，a kind of “inner clock”.
This __9__ may not seem to be very important.However，it was later found that not just plants but also __10__，including man，have this “inner clock” which __11__ the working of their bodies and influences their activities.Men，then，are also influenced by this mysterious __12__.Whether we wish it or not，it affects such things in our life as our need for sleep，our need for food.
In the past，this did not really __13__ because people lived in natural condition.In the __14__ world，things are different；now there are spacemen，airplane pilots and，in ordinary life，a lot of people who have to work at night.It would be very __15__，then，to know more about the “inner clock”.Such things as flowers might help us understand more about ourselves.
1．A．familiar B．strange C．similar D．special
2．A．partly B．personally C．really D．willingly
