英语完形填空At the beginning of this century,medical scientists ma

英语完形填空
At the beginning of this century,medical scientists made an interesting discovery; we are built not just of flesh and blood but also of time.They were 21 to show that we all have “a body clock” 22 us,which controls the 23 and fall of our body energies,24 us different from one day one to the next.
24 us different from one day one to the next.这句话是否有问题？