Small experimental vacuum tubes can operate in heat that makes semiconductor components fail. Any component whose res...

shunhe on September 18, 2020

Hi @liwenong28,

Thanks for the question! So I’ll start off here with what this question is asking: it’s asking us for something that has to be true if the statements above are true, which means that this is a must be true question! And for must be true questions, we’re either looking for something that’s already stated in the passage, or is a direct inference from statements in the passage, or is something we can get from combining statements in the passage. And we want to know that it 100% has to be true.

So now let’s take a look at what we’re told. Small experimental vacuum tubes can operate in heat that makes semiconductor components fail. Any component whose resistance to heat is preferable for use in digital circuits, but only if that component were also comparable in all other significant respects. But vacuum tubes’ maximum current capacity isn’t comparable to that of semiconductors right now.

Notice that we can diagram this. We know that

Resistance to heat greater than semiconductors —> Preferable for use in digital circuits
Preferable —> Comparable

~comparable in all other significant respects

So we can apply the contrapositive to this statement to get

~Comparable —> ~Preferable

And so we know that the vacuum tubes aren’t preferable as well, and that’s what (A) tells us. Since this is a direct logical inference, it must be true, and is the correct answer.

Hope this helps! Feel free to ask any other questions that you might have.