Simple past or present perfect when talking about a general event?

Question

When we want to convey a general event that happens earlier, which tense should I use: simple past or present perfect?

Here are some examples I came up with (I am not sure the examples are correct):

(1) If your kid swallowed / has swallowed the toy, you have to call the ambulance immediately.

(2) If you find your kid swallowed / has swallowed the toy, you have to call the ambulance immediately.

(3) If a person did / has done something nice to you, you have to say thank you.

(4) When a person didn't sleep / hasn't slept enough, she can be mad easily during the day.

(5) When you finished / have finished a meal, you have to wash your hands.

Answer 1

Normal usage:

1. • If a person does something nice for you, you have to say thank you. [in general, a simple present is used]
2. • If a person did something nice for you [specific act at a specific moment in the past], you have to say thank you. [a specific act in the past even if the date or time is not given]
3. • If a person has done something nice for you [in the past at the time of speaking but without referring to when the person did it], you have to say thank you. [a non-specific time in the past, but, this occurs in a non-specific past]

The difference between 2 and 3 is this:

• 2 refers to a specific time or moment in the past in relation to the present.
• 3 refers to a time in the past, the specificity of which is not important; what is important is that it is merely at some past time at the time of speaking in the present.

The use of 2 or 3 is dictated by what the speaker wants to say, nothing else.