2016考博英語改錯模擬練習題及答案解析

The term biological clock is applied to the means which living __1__things adjust their activity patterns, without any obvious cue, the __2__　time of day, or the month, or the year. They are affected but little,if at all, by drugs, chemicals, or wide temperature differences—factors may alter substantially the rates of all ordinary processes of __3__the body.
　　The nature of the biological clocks mechanism is still a mystery __4__two quite different theories have been advanced to account to __5__them. According to the first of these theories, each individual have envolved, aided by natural selection, an adaptation to the rhythmic __6__environment. It has now become independent on the environment __7__according to this view, the clocks are not perfect timers.