[单项选择]Because of the great speed of light, we see a lamp light up almost at the exact moment （）.
A. we turn it on
B. when we turn on it
C. that we turn on it
D. which we turn it on

[单项选择]Because of the great speed of light, we see a lamp light up almost at the exact moment______.
A. we turn it on
B. when we turn on it
C. that we turn on it
D. which we turn it on

[填空题]In this light, if we can ______________(善用时间), there can surely be no doubt that we will get some where.

[填空题]In light therapy, you just sit near a special lamp for _______________ every morning.

[单项选择]

All we have a clock located inside our brains. Similar to your bedside alarm clock, your internal clock runs on a 24-hour cycle. This cycle, called a circadian rhythm, helps control when you wake, when you eat and when you sleep.
Somewhere around puberty, something happens in the timing of the biological clock. The clock pushes forward, so adolescents and teenagers are unable to fall asleep as early as they used to. When your mother tells you it’s time for bed, your body may be pushing you to stay up for several hours more. And the light coming from your computer screen or TV could be pushing you to stay up even later.
This shift is natural for teenagers. But staying up very late and sleeping late can get your body’s clock out of sync with the cycle of light and dark. It can also make it hard to get out of bed in the morning and may bring other problems, too. Teenagers are put
A. it has a cycle of 24 hours
B. it controls when we wake, when we eat and when we sleep
C. it can alarm any time during 24 hours
D. it is a cycle also called circadian rhythm

[简答题]It is only when we cannot see perfectly that we realize how important our eyes are.