[填空题]The term biological clock is applied to the means, which living things 67. ______
adjust their activity patterns, without any obvious cue, the time of day, or 68. ______
the month, or the year. They are affected but little, if at all, by drugs,
chemical, or wide temperature differences—factors may alter substantially 69. ______
the rates of all ordinary processes of the body.
The nature of the biological clocks mechanism is still a mystery. Two 70. ______
quite different theories have been advanced to account to them. According 71. ______
to the first of these theories, each individual have evolved, aided by natural
selection, an adaptation to the rhythmic environment. It has now 72. ______
become independence on the environment. According to this view, the clocks 73. ______
are not perfect timers. They require regular corrections by the natural light
and tide cycles and the changed

[填空题]The term biological clock is applied to the means, which living things 67. ______
adjust their activity patterns, without any obvious cue, the time of day, or 68. ______
the month, or the year. They are affected but little, if at all, by drugs,
chemical, or wide temperature differences—factors may alter substantially 69. ______
the rates of all ordinary processes of the body.
The nature of the biological clocks mechanism is still a mystery. Two 70. ______
quite different theories have been advanced to account to them. According 71. ______
to the first of these theories, each individual have evolved, aided by natural
selection, an adaptation to the rhythmic environment. It has now 72. ______
become independence on the environment. According to this view, the clocks 73. ______
are not perfect timers. They require regular corrections by the natural light
and tide cycles and the changed

[单项选择]Passage Four A biological clock is what tells plants, animals, and other organisms how to organize their time. This ‘clock’ helps plants and animals change their routine when they move to places with different climates and environments. Most biological clocks are based on the movement of the sun and follow a twenty-four hour cycle called a circadian rhythm. Some animals sleep only at night, making them diurnal. Animals that sleep during daytime are nocturnal. Flowers are diurnal because they close their petals at night but they open again in the morning. Bats sleep in the daytime so they are nocturnal. Some biological clocks also follow an annual cycle, especially in animals that have annual migrations. Animals that have annual cycles do different things at different times of year. Their actions are determined by the seasons. Different animals can live in the same area when their biological clocks make them look for food at different times of day. This process also
A. human
B. flowers
C. bats
D. cows

[单项选择]

Every living thing has what scientists call a biological clock that controls behavior. The biological clock tells (1) when to form flowers and when the flowers should open. It tells (2) when to leave the protective cocoons and fly away, and it tells animals and human beings when to eat, sleep and wake.
Events outside the plant and animal (3) the actions of some biological clocks. Scientists recently found, for example, that a tiny animal changes the color of its fur (4) the number of hours of daylight. In the short (5) of winter, its fur becomes white. The fur becomes gray brown in color in the longer hours of daylight in summer.
Inner signals control other biological clocks. German scientists found that some kind of internal clock seems to order birds to begin their long migration (6) twice each year. Birds (7) flying become res
A. things
B. parts
C. cells
D. actions