I took part at a English olympiad last week. And while I was doing the following task I faced with interesting question.

I wonder if Mary has reached home yet? She left too late to catch the bus.

"has reached" is used because period of time isn't finished but could I use Present Perfect ("has left") instead of "left"?

• You take part in something, and you were faced with an interesting question.
– TimR
Commented Mar 5, 2017 at 15:10
• @TRomano, ok, I'm sorry that I wrote it with mistakes. Actually I'm not a native and was in harry writing it. Don't be mad at me. Commented Mar 5, 2017 at 15:53
• Don't worry about it. All learners make mistakes. I was just pointing them out to you. You should feel free to ask questions. They don't have to be perfect.
– TimR
Commented Mar 5, 2017 at 15:55
• @TRomano, thank you. I'll take it into consideration. Commented Mar 5, 2017 at 17:46

Has she left too late to catch the bus?

if there is still a possibility of her catching the bus. The bus may not have reached the bus-stop yet. Under those circumstances, the present perfect is valid.

She will miss the bus because she has left too late.

But if you know that she did miss the bus, then it is something that took place already; it is in the past:

She missed the bus because she left too late.

The missing of the bus does not itself continue into the present, even if downstream results of missing the bus do continue into the present. The act of missing the bus occurred in the past.

And if you are explaining, at some later time, why she missed the bus back then:

She missed the bus because she had left too late.

• So it is aceptable to use Present Perfect in the second statement? Commented Mar 5, 2017 at 17:51
• What is "the second statement"?
– TimR
Commented Mar 5, 2017 at 17:55
• "She ___ to late to catch the bus". Commented Mar 5, 2017 at 17:56
• Yes. My second example shows that use ("...because she has left too late"). She has not yet missed the bus. It is not a thing of the past.
– TimR
Commented Mar 5, 2017 at 17:57
• Thank you. Great explanation. Wold you mind reading one of my topics? Commented Mar 5, 2017 at 17:59

Actually if you feel you must use the perfect tense, you would use the past perfect in the second sentence, because it describes previous action that takes place before some other (unspoken) action:

She had left too late to catch the bus.

The problem with your example is more the first sentence, where the present perfect is not really justified in this context. Normally a native speaker would say simply:

I wonder if Mary is/got/arrived home yet?

The present perfect ("has left") is fine, but not if you assume it's been long enough for her to get home. The present perfect suggests very little time has passed since she left:

I wonder if Mary will get home OK? She has left too late to catch the bus.

Note all these are more about contextual agreement than grammar. The perfect tense always implies a temporal relationship, which should make sense.