成人每天的维生素D摄入量为“0.00000046”，用科学计数法表示为（   ）。

(单选题)All the following participles functions as an attributive ex (单选题)Which of the following sentences express “probability”? (单选题)John’s not been to New York, ______. (单选题)Somebody is knocking at the door; I wonder who ______ is. (单选题)Reading can satisfy ______ hunger that comes from the desire (单选题)He is a student of Tsinghua University, majoring ______ phys (单选题)方程组表示的是（ ）。 (单选题)曲线在点处的切线方程是（ ）。 (单选题)不定积分（ ）。 (单选题)极限（ ）。