formulaic subjunctive; "simple past" vs "present perfect"

"A Comprehensive Grammar of the English Language" by Quirk et al
P.157
3.60 The formulaic subjunctive
Be it noted that .....
Be that as it may, we ....

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Using Simple Past or Present Perfect in a question
http://groups.google.com/group/alt.usage.english/browse_thread/thread/2326763564ecba38#


Present perfect (its use in UK, younger people) (English Grammar in use, Cambridge University, Murphy)
http://www.englishforums.com/English/PresentPerfectTense/bcdqqc/post.htm