"it had been raining"="it stopped raining"?
http://groups.google.com/group/alt.usage.english/browse_thread/thread/85452a6d6a8f0341/d3ea1fb91441063b
was/had been studying ...
http://groups.google.com/group/alt.usage.english/browse_thread/thread/70b5d1c3b636aaee/a49992deb8f5d639
(Note: "had been" version implies ... stopped -> "Not necessarily". This interpretation (kinda) matches M.S.'s in "Practical English Usage")
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Past Perfect Continuous
http://www.englishpage.com/verbpage/pastperfectcontinuous.html
......
He was tired because he had been exercising so hard.
This sentence emphasizes that he was tired because he had been exercising over a period of time. It is possible that he was still exercising at that moment OR that he had just finished.
.....
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(Azar)
past progressive vs past perfect progressive
http://thegrammarexchange.infopop.cc/eve/forums/a/tpc/f/340600179/m/1991024044
2. .. had been doing ... when ....
(In the second sentence of your posting ..... may or may not have continued afterwards.)
Targeting Grammar Grades 5-6
http://books.google.com/books?id=KNGjtJXsspMC&pg=PA82
http://www.amazon.com/Targeting-Grammar-Teacher-Created-Resources/dp/1420624377/ref=sr_1_1?s=books&ie=UTF8&qid=1280439509&sr=1-1
Grammar Practice for Grades 3-4
http://www.amazon.com/Grammar-Practice-Grades-Peter-Clutterbuck/dp/0743936213/ref=pd_cp_b_1
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Grammar and Punctuation 一系列，從Grade 1-6
今天在逛書局時突然瞄到的。兒童書區一般我都是直接走過，這次碰巧看到，好奇之下我拿來翻一翻。怎麼說呢，我的第一個念頭是「這會是很好的教材」，對象的話... 小學生... or 大一點的也可以，甚至是成人也可以，只是接受度....
(我讀了Customer Reviews. 很多是家長買來homeschooling用的)
