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【单选题】For more than thirty years after astronauts first set foot on the Moon, scientists have been unable to unravel the mystery of where the Earth’s only satellite came from. But now there is direct eviden...
A.
the differences between the Earth and the Moon
B.
how man manages to set foot onto the Moon
C.
the collision between the Earth and the Moon
D.
the origin of the Moon
【单选题】Mars fascinates scientists because of its similarity to Earth, and it fascinates the public because our myth of "Martians" is a vision of life beyond Earth. The Mars 62 continues with the launch of ...
A.
extremes
B.
extracts
C.
terminals
D.
radicals
【单选题】Mars fascinates scientists because of its similarity to Earth, and it fascinates the public because our myth of "Martians" is a vision of life beyond Earth. The Mars 62 continues with the launch of ...
A.
thus
B.
however
C.
so
D.
but
【单选题】The History of the Atomic Bomb On August 2, 1939, just before the beginning of World War II, Albert Einstein wrote to then President Franklin D. Roosevelt. Einstein and several other scientists told R...
A.
Franklin D. Roosevelt.
B.
Nazi Germany.
C.
Albert Einstein and other scientists.
D.
The Second World War.
相关题目：
【判断题】自然界中碳有三种同位素：碳-12，碳-13和碳-14。
A.
正确
B.
错误
【单选题】For more than thirty years after astronauts first set foot on the Moon, scientists have been unable to unravel the mystery of where the Earth’s only satellite came from. But now there is direct eviden...
A.
the differences between the Earth and the Moon
B.
how man manages to set foot onto the Moon
C.
the collision between the Earth and the Moon
D.
the origin of the Moon
【多选题】天然铀有哪几种同位素()
A.
铀234
B.
C.
铀236
D.
铀238
【单选题】下列互为同位素的一组是
A.
和
B.
和
C.
和
D.
和
【单选题】连铸机结晶器用Cs-137同位素检测结晶器内( )。
A.
凝固层厚度
B.
钢水质量
C.
钢液面高度
【单选题】同位素中（）。
A.
质子数相同，中子数不同
B.
质子数相同，中子数相同
C.
中子数相同，质子数不同
D.
中子数、质子数均不相同
【单选题】The History of the Atomic Bomb On August 2, 1939, just before the beginning of World War II, Albert Einstein wrote to then President Franklin D. Roosevelt. Einstein and several other scientists told R...
A.
Franklin D. Roosevelt.
B.
Nazi Germany.
C.
Albert Einstein and other scientists.
D.
The Second World War.
【多选题】放射性同位素按其毒性分为（）。
A.
极毒组
B.
无毒组
C.
高毒组
D.
低毒组
E.
中毒组
【单选题】放射性同位素的半衰期决定于其（）
A.
放出射线的能量
B.
放出射线的强度
C.
放射性同位素本身的性质
D.
以上都是
【单选题】今有氧的同位素16O、17O、18O，氢的同位素H、D，从水分子的原子组成来看，可组成的水分子可以有
A.
3种
B.
6种
C.
9 种
D.
12种
【多选题】放射性同位素防护的方法有:()。
A.
时间防护
B.
距离防护
C.
屏蔽防护
D.
稀释