题目内容：
请根据短文的内容，回答题。What Is the Coolest Gas in the Universe?
What is the coldest air temperature ever recorded on Earth? Where was this low temperature recorded? The coldest recorded temperature on Earth was -90℃, which __________ (51) in Antarctica (南极洲 ) in 1983.
We encounter an interesting situation when we discuss temperatures in __________ (52).
Temperatures in Earth orbit (轨道) actually range from about + 120℃ to -120℃. The temperature depends upon __________ (53) you are in direct sunlight or in shade. Obviously, -120℃ is colder than our body can __________ (54) endure.
The space temperatures just discussed affect only our area of the solar __________ (55).Obviously, it is hotter closer to the Sun and colder as we travel __________ (56) from the Sun.
Scientists estimate temperatures at Pluto are about -210℃. How cold is the lowest estimated temperature in the entire universe? Again, it depends upon your __________ (57). We are taught it is supposedly __________ (58) to have a temperature below absolute zero, which is -273℃, at which atoms do not move. Two scientists, Cornell and Wieman, have successfully __________ (59)down a gas to a temperature barely above absolute zero. They won a Nobel Prize in Physics in 2001 for their work--not a discovery, in this case.
Why is the two scientists' work so important to science?
In the 1920s, Satyendra Nath Bose was studying an interesting __________ (60) about special light particles (微粒) we now call photons (光子). Bose had trouble __________ (61) other scientists to believe his theory, so he contacted Albert Einstein. Einstein's calculations helped him theorize that atoms __________ (62) behave as Bose thought--but only at very cold temperatures.
Scientists have also discovered that ultra-cold (超冷) atoms can help them make the world's atomic clocks even __________ (63) accurate. These clocks are so accurate today they would only lose one second __________ (64) six million years! Such accuracy will help us travel in space because distance is velocity (速度) times time (d=υt). With the long distances involved in space__________ (65), we need to know time as accurately as possible to get accurate distance.
_________ A．operated
B．occurred
C．opened
D．offered
参考答案：
答案解析：