問大家一d tense 問題

The perfect tense is not in the time of action,but of its occurrence and in its result.The present perfect tense, though it indicates an action took place in the past, is associated with the present idea of now,eg:-Mary has just received a letter.(up to now)(just now)( no need to mention possibly to the future),which means for an action just concluded when the resulting state is still present and today,
eg:-Mary has received a letter for 2 sec.
Mathematic meticulously 10:02-10:00=00:02 (for 2 sec)

no,the time has past two minutes.

Mary 係早上十點收到一封信，咁係十點零二秒可唔可以講"Mary has received
a letter." - correct tense

我認為可以,因為十點零二秒,姐係十點後,已經收完果一封信

同一人,經常問些鷄蛋裡挑骨頭的問題,而自己心中己有答案,又可必問人呢﹖

2014-01-18 20:24:28 補充：
一,兩秒都計得咁清楚,應問數學老師。