In the secondary structure of roots, xylem rays and phloem rays belong to ( ). A: Secondary rays B: Vascular rays C: Pith rays
In the secondary structure of roots, xylem rays and phloem rays belong to ( ). A: Secondary rays B: Vascular rays C: Pith rays
以下属于直接电离辐射的是（） A: X-rays B: γ-rays C: β-rays D: neutrons
以下属于直接电离辐射的是（） A: X-rays B: γ-rays C: β-rays D: neutrons
The anti-UV mutation of microorganisms must be induced by ultraviolet rays
The anti-UV mutation of microorganisms must be induced by ultraviolet rays
Ultraviolet rays from the Sun can cause which of the following?
Ultraviolet rays from the Sun can cause which of the following?
X-rays and gamma rays can be used to detect and treat cancer ______.
X-rays and gamma rays can be used to detect and treat cancer ______.
The seven rays of the Statue of Liberty’s crown symbolize the seven continents of the world.
The seven rays of the Statue of Liberty’s crown symbolize the seven continents of the world.
The anti-UV mutation of microorganisms must be induced by ultraviolet rays A: 正确 B: 错误
The anti-UV mutation of microorganisms must be induced by ultraviolet rays A: 正确 B: 错误
What is the essence of cathode rays? A: proton B: neutron C: electron D: atom
What is the essence of cathode rays? A: proton B: neutron C: electron D: atom
The sun’s rays falling upon photo-electric cells, the whole apparatus will automatically go into operation.
The sun’s rays falling upon photo-electric cells, the whole apparatus will automatically go into operation.
to send out rays; to beam or shine A: adiate B: eassure C: premise D: simulate
to send out rays; to beam or shine A: adiate B: eassure C: premise D: simulate