+0

What's the difference?


Who broke the window?

Who has broken the window?


Who wrote this book?

Who has written this book?

+1
TicceWhat's the difference?

The core meaning is about the same, but those tenses are used in different contexts. There are many books and websites that explain these differences.

Briefly, the past is used when the action was completed in the past and has little or no effect on the present situation, and the present perfect is used when the past action continues into present time or, if completed earlier, is still relevant to the present situation.

< past ---------------------------- present ----------- future >
[PAST SIMPLE] ----- time gap ----- ^
< ............... PRESENT PERFECT .............. ]

CJ

Comments  
Students: Are you brave enough to let our tutors analyse your pronunciation?

Jim. basically I know that difference. But I don't see a practical difference in meaning between the two?

Both actions happen in the past. But there must/can be a relevance/effect on the present. 1 Who decides whether the sentence has or hasn't an effect on the present? 2 How does this effect on the present manifest itself? What factors conduce to the formation of this effect?


Who has written this book? - Who wrote this book? - (What kind of effect on the present can there be as such in this question?) The answer to the two questions, I suppose, should be the same or am I wrong?

Ticce

What's the difference?


Who broke the window?

Who has broken the window?


Who wrote this book?

Who has written this book? = who is the author of this book?

The green ones are idiomatic and natural. The pink ones are grammatical but not common.

When you ask about something you found just happened, it is usually in simple pas tense. e.g. Who ate my sandwich?

Present perfect is almost never used in the fashion you asked about. But in narratives, statements, Present perfect is fine. e.g. I have visited Hong Kong 5 times. Now, let me reiterate something. One may be surprised and made this questioning statment: " Really, you have visited Hong Kong 5 times? " In this context, it is fine.

Ticce1 Who decides whether the sentence has or hasn't an effect on the present?

The speaker. But the contents of the sentence can also give clues that influence the speaker's choice. In fact, that happens in the book-writing example. The book is already finished. Time has passed since then. So the usual choice here would be Who wrote this book?

It would require a stretch to set up a scenario for Who has written this book? But we might do it, "just for laughs". Suppose there is a course in which the participants must each write a book. At the end of the course a panel of experts, not knowing who the authors are, chooses the best book. When the award is given, the director of the writing school holds up the winning book for all the assembled authors to see, reads the title aloud, and asks Who has written this book? (Yes, it's a stretch.)

Ticce2 How does this effect on the present manifest itself? What factors conduce to the formation of this effect?

In some cases it is pure convention. That's why learners are encouraged to remember certain formulas like Have you ever ...? and its answers Yes, I've ... or I've never ... when reporting life experiences.

In some cases it's the presence of something in the environment or in the topic of the conversation that triggers the use of the present perfect.

Looking directly at a broken window: Who has broken this window? But in listening to a friend recount a story from her childhood in which a broken window comes up as part of the story, in our excitement to find out what happens next, we might blurt out So who broke the window? The window is not here-and-now. It's in a story whose consequences have played out long ago, so the present perfect is inappropriate.


In most cases you won't go wrong with the simple past. Most present perfect sentences could just as easily be stated in the past (including those in my examples above). The opposite substitution is not so often possible.

CJ

Students: We have free audio pronunciation exercises.