I am not able to understand why you say that the first premise: Classification based on mechanical action does not have support and that the author is just laying it out just like that without any justification. The last premise indicates that because strings are hit by the hammers, it produces sound, which I am aware is a support to the conclusion but can it also not be a support for the first premise since hammering is a mechanical action described here.

I was confused for a second about what the conclusion is between the 2 since there seemed to be support for the first premise, but seeing that there was more clarifying evidence about piano being a percussion instrument. I picked the piano argument as a conclusion.

Please clarify if I am misunderstanding something.

I am confused about 5.2.

If we go about this question by answering 'why has there been an increase in air pollution? It makes sense to say that 'because industrial revolution and so and so. So, shouldn't the line where 'increase in pollution' be the conclusion and the line about 'fossil fuel combustion and industrial processes' be the premise?

I read the explanation too.

Based on the last line of the explanation,

'From this observation, the author concludes a causal relationship, that the increase in air pollution is due to the industrial revolution.'

Isn't it clear from here that we are trying to say that 'increase in air pollution happened because of industrial revolution', thus asserting what I said before?

For question 5,

In wish-amend → (petition-30 → maj-vote), it is mentioned in solutions that just because at least 30 votes were collected, both the sufficient conditions have been met, which refers to wish-amend and petition-30.

If petition-30 condition (which is a necessary condition) is fulfilled, isn't it that we cannot assume anything about 'wish-amend' since if we know that necessary is present, we cannot say anything about the sufficient condition? What if people collected at least 30 signatures because they don't want to amend the law? This is what I understood based on the previous lessons. But not sure why it would be stated this way here that both the sufficient conditions have been met merely because the necessary condition (petition-30) was met when it should be that petition-30 is the sufficient condition that was met, that resulted in majority vote being proposed.