Concrete used in water-retaining structures or exposed to weather or other severe exposure condition must be virtually（）or（）.
正确答案：impermeable watertight
相关文章
TEMs produce（）高分辨率, two-dimensional images, allowing for a wide range of applications.
TEMs produce（）高分辨率, two-dimensional images, allowing for a wide range of applications. 正确答案：high-resolution
Since all groups have their（）特征振动频率, information regarding molecular structure can be gained from the spectrum.
Since all groups have their（）特征振动频率, information regarding molecular structure can be gained from the spectrum. 正确答案：characteristic vibrational frequency
Thes analysis etechniques for chemical composition could be classified as（）（光谱学）, which is study of the interaction between matters and radiated energy.
Thes analysis etechniques for chemical composition could be classified as（）（光谱学）, which is study of the interaction between matters and radiated energy. 正确答案：spectroscopy
In SEM, magnification is controlled by objective lens power.
In SEM, magnification is controlled by objective lens power. A.正确B.错误 正确答案：错误
The scanning electron microscopy（SEM）uses a focused beam of high-energy electrons to generate a variety of signals at the inside of solid specimens.
The scanning electron microscopy（SEM）uses a focused beam of high-energy electrons to generate a variety of signals at the inside of solid specimens. A.正确B.错误 正确答案：错误
