海洋是一个巨大的化学资源宝库．海水综合利用的部分流程如下：

已知：Br₂的沸点为59℃，微溶于水，有毒性和强腐蚀性．

完形填空

     Mr Green works in an office in France.  1  Saturday,  he went to the office to do some work. When he got on the elevator(电梯) , it stopped between the   2  . Mr Oreen could not get out of the elevator. He started to  3  but no one  4   him. Then Mr Green remembered that it was a holiday in France. No one 5 going to come to work until Tuesday.

     There was   6  for him to do. He had to wait. With nothing to eat   7drink,  Mr Green slept for most of the time. Early Tuesday morning,  his  8  came to work and found the elevator was not working. When the elevator was  9  , Mr Green came out. He was cold,  weak and tired. He had been in the elevator for about sixty-four  10  ! Now Mr Green says, "I will only use elevators if they have a telephone in them. "

化石记录显示，在越古老的地层里成为化石的生物是（）