+0
A. I don't think I will have any problems operating the machine.
B. I don't think I would have any problems operating the machine.

C. I don't think my health can affect my performance.
D. I don't think my health could affect my performance.

I wonder what the difference is between the sentences in each pair. Could you please explain?
Does it have something to do with being humble or being confident?

I think "will" and "can" sound like very confident, whereas "would" and "could" sound humble or suggest some reservations. I'm really not sure, though. Thank you in anticipation of your response.
Comments  
AnonymousI think "will" and "can" sound like very confident, whereas "would" and "could" sound humble or suggest some reservations. I'm really not sure, though. Thank you in anticipation of your response.
Yes, you're pretty much spot-on with your interpretation. That's how I would interpret it, too.

"would" and "could" express a greater level of uncertainty, or even a hypothetical situation:

A. I don't think I will have any problems operating the machine.
B. I don't think I would have any problems operating the machine.

A. You probably have already been designated to operate the machine, and you are fairly confident that you won't have any problems with it.
B. You think you would have no problems if you were chosen to operate the machine.
Thank you for your helpful explanation.
ozzourti"would" and "could" express a greater level of uncertainty, or even a hypothetical situation:

A. I don't think I will have any problems operating the machine.
B. I don't think I would have any problems operating the machine.

A. You probably have already been designated to operate the machine, and you are fairly confident that you won't have any problems with it.
B. You think you would have no problems if you were chosen to operate the machine.
Just to clarify, in this example, does the level of certainty using "will/would" relates to how sure I'll be chosen to operate the machine or does it relate to how sure that I won't have any problems operating it?

If I were asked the question "Would you have any problems operating the machine?" even though you were not yet chosen to do it, can I answer A to show I'm confident that I can do it?

A. I don't think I will have any problems operating the machine.
Students: We have free audio pronunciation exercises.
If I were asked the question "Would you have any problems operating the machine?" even though you were not yet chosen to do it, can I answer A to show I'm confident that I can do it? A. I don't think I will have any problems operating the machine.

No; A shows confidence in your being chosen, not in your ability to operate it.
Thank you, Mister M, for your input here.

I see the level of certainty or confidence that something will happen relates to what is said in the if-clause, not about the main clause. Thank you very much for this clarification.

1. Just some follow-up questions, for an interview, if I were asked "How do you feel about a co-worker not cooperating?", which is better to say: a or b?
2. Do you think a is better because I'm open to the possibility of coming across such a person?
3. Or do you think b is better because I'm only talking about a hypothetical situation?

a. If I come across a co-worker, who is uncooperative, I don't think I will have a problem handling him.

b. If I came across a co-worker, who was uncooperative, I don't think I would have a problem handling him.
1. Just some follow-up questions, for an interview, if I were asked "How do you feel about a co-worker not cooperating?", which is better to say: a or b?-- B

2. Do you think a is better because I'm open to the possibility of coming across such a person?-- No; it is more than that; it is a real expectation.

3. Or do you think b is better because I'm only talking about a hypothetical situation?-- Yes; we never (theoretically) expect a spate of uncooperation; we expect that the new manager (you) will instill cooperation proactively.

a. If I come across a co-worker who is uncooperative, I don't think I will have a problem handling him.
b. If I came across a co-worker who was uncooperative, I don't think I would have a problem handling him.
Teachers: We supply a list of EFL job vacancies
I would use B, then. OK, Thank you, Mister M.
I've really learned a lot from you in this thread. Emotion: smile
It is also less formal to use Can and Will VS more formal to use Could or Would