For many years, scientists couldn’t figure out how atoms and molecules combined to make living things. Plants, fish, dinosaurs, and people are made of atoms and molecules, but they are put together in a more complicated way than the molecules in the primitive ocean. What’s more, living things have energy and can reproduce, while the chemicals on the Earth 4 billion years ago were lifeless.
After years of study, scientists figured out that living things, including human bodies, are basically made of amino acids, nucleotide bases, lipids and water. How could such complicated molecules have been formed and have started to interact in the primitive soup Scientists were stumped.
Then, in 1953, two scientists named Harold Urey and Stanley L. Miller did a very simple experiment to find out what had happened on the primitive Earth. They set up some tubes and bottles in a closed loop, and put in some of the same gases that were present in the atmosphere
A. 4 billion years ago.
B. After seven days.
C. Many years ago.
D. In 1953.
For many years, scientists couldn’t figure out how atoms and molecules combined to make living things. Plants, fish, dinosaurs, and people are made of atoms and molecules, but they are put together in a more complicated way than the molecules in the primitive ocean. What’s more, living things have energy and can reproduce, while the chemicals on the Earth 4 billion years ago were lifeless.
After years of study, scientists figured out that living things, including human bodies, are basically made of amino acids, nucleotide bases, lipids and water. How could such complicated molecules have been formed and have started to interact in the primitive soup Scientists were stumped.
Then, in 1953, two scientists named Harold Urey and Stanley L. Miller did a very simple experiment to find out what had happened on the primitive Earth. They set up some tubes and bottles in a closed loop, and put in some of the same gases that were present in the atmosphere
A. water
B. the liquid sample
C. a closed loop
D. an electric spark
Text 3
For years I. O.C. Czar Juan Antonio Samaranch has exhibited a pronounced ambivalence about drug use, and certainly his stance has allowed a number of golden boys and girls to keep their images shiny while doping. Careful athletes can easily beat the system that is in place to catch drug abusers. Unscrupulous sports federations can tailor testing schedules and tip off their constituents. Steroid creams can be flushed from the system in 24 to 48 hours. And for some of the most commonly used enhancers, such as erythropoietin (EPO), there are still no institutionalized teats. It is said that EPO, which increases stamina by boosting an athlete’s red blood cell count, can improve an athlete’ s performance in a 20-minmn by 30 sec., but it is otherwise a nightmare of a drug. Overdose on EPO, and the blood becomes too thick for the heart to pump. EPO is believed to be the culprit in no fewer than 25 mysterious deaths among world-class cyclists since 1987.
A. The participation of cheaters
B. The untested EPO-use
C. Lack of new world records
D. Unannounced and out-of-competitive test
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