The first detailed study of magpie attacks in Australia

[RaviK465]

Got it. Thanks for the help Stacey !

[JbhB682]

Hi Experts - was a bit surprised by Ron post below

Link to post - https://www.manhattanprep.com/gmat/foru ... ml#p123937

"by the time they reach adulthood, they have been attacked..."
—> GENERAL STATEMENT (no specific timeframe)

"by the time they reach adulthood, they will have been attacked..."
—> statement about FUTURE events

in the second case, you might expect "by the time they will reach...", but no such thing exists in english. (if something after "if" represents the future, then it's written in the same way as the present.)

How come the Present perfect is being used for GENERAL STATEMENTS (no specific time frame) as mentioned by Ron in the blue font above

Isn't GENERAL STATEMENTS / UNIVERSAL FACTS reserved for Present tense only ?

i thought if you want to use a GENERAL statement - you have to use Present tense

Present perfect on the other hand per the Manhattan Guide is something that started in the past and is still going on today or something that started in the past and has ended in the past (but its ending in the past, still has an impact on the present)

You dont use Present perfect tenses when talking about General statements / Universal truths.

[Whit Garner]

"by the time they reach adulthood, they have been attacked..."
—> GENERAL STATEMENT (no specific timeframe)

The "general statement" Ron is referring to is the verb "reach." The fact that all of this is happening by the time adults reach adulthood (as a general rule), we use present tense.

As for the "have been," because the attacking birds would have happened before these people reach adulthood, we have to move that verb into a test sometime before the present (and past perfect is great for that here).