If John did not come to work yesterday, he was probably ill.
This isn't any of the conditionals you mention. It is not an example of one statement depending on another; it is a statement of logic that one thing must mean another.
The speaker is indicating that he does not know for certain whether John came into work or not - but if it is true that he didn't,...
Could can either have a past meaning (=was able to) or a conditional meaning (=would be able to). For example, in the sentence "When I was younger I could run five miles", "could" means "was able to" and serves as the past tense of "can".
As you know, in the Second Conditional, the simple past is used in the condition ...
The "First, second, third conditionals" are lies told to children. They help to give some structure to learning the conditional structures in English, but don't give every possible combination of tenses.
Here it is clear that the condition is "real". It is factual so this functions like a "zero conditional". It expresses an ...
I'm not entirely sure I follow what you're saying, but here's how I would go about it:
A. If it is an eagle, then it is a bird. (E implies B)
B. If it is a bird, then it is an eagle. (B implies E)
C. A bird is the same thing as an eagle. (E implies B and B implies E)
(I'm not sure I have C right; it's been a while since I took a logic course. I understand ...
India’s concern is that if it takes a decision that irks Generals in Myanmar, China would get closer to the junta and use the opportunity to hurt India’s interests in Myanmar.
Q. But here, Is the first part of the sentence “India’s concern is that If it takes a decision” hypothetical? I don’t think so. Then why would is used in later part?
If it's a bird, then it's an eagle.
is a way writing of B in English. It's not the only way. Other possible answers could be
It is a bird implies that it is an eagle
All birds are eagles.
Note that "If it is a bird then it could be an eagle" is incorrect. It doesn't express Q -> P since P is "it is an eagle" not "It ...
The existing answer is correct, but a second correct answer is to use "unless":
Unless a polygon has exactly four sides, it is not a quadrilateral.
We could also say:
A polygon is a quadrilateral only if it has exactly four sides.
If we wanted to state in a single sentence both that four-sided polygons are quadrilaterals and that non-four-sided ...