Could you recommend me any grammar taskbook like Murphy with a lot of tasks and explanation of perfect tense? I haven't quite understood the meaning of the perfect tense and all cases when it should be used. I have to train much more...
closed as not constructive by choster, aedia λ, Hellion, MετάEd, cornbread ninja 麵包忍者 May 30 '13 at 19:38
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