Which of the following are considered petroleum plants?

In the study of a transistor as an amplifier,if $\alpha = \frac{I_C}{I_E}$ and $\beta = \frac{I_C}{I_B}$,where $I_C, I_B$,and $I_E$ are the collector,base,and emitter currents,respectively,then:

$A$ thin hollow sphere of mass $m$ is completely filled with a liquid of mass $m$. When the sphere rolls with a velocity $v$,the kinetic energy of the system is (neglect friction).

Which of the following values indicates hypertension?

An integrating factor of the equation $(1+y+x^2 y) dx+(x+x^3) dy=0$ is

Which of the following is logically equivalent to $\sim(\sim p \Rightarrow q)$?