半径为１的球面上有四个点A，B，C，D，球心为点Ｏ，AB过点Ｏ，,,, 则三棱锥的体积为（ ）
Santa, what are you doing? I ___ presents __ all the children.
Happy New Year. A.Thank you. B.Happy New Year. C.Merry Christmas.
What are you doing? I _____ presents.
It’s nice o’clock.Tim _____ table tennis.
I _____ ___ umbrella.That woman ____ ____ umbrella, too. A.has an…has…an, B.has a…has a, C.have an…has an
,
,
, 则三棱锥
的体积为（ ）
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