[填空题]
Three $240-\Omega$ resistors can be connected together in four different ways, making combinations of series and/or parallel circuits. What are these four ways, and what is the net resistance in each case?
The resistors can all be connected in series $\Omega$
The resistors can all be connected in parallel. $\Omega$
Two resistors in series can be placed in parallel with the third. $\Omega$
Two resistors in parallel can be placed in series with the third. $\Omega$
