This book ___ Lucy's.Tom's name is on its cover.A.can't be B

題目：

This book ___ Lucy's.Tom's name is on its cover.A.can't be B.mustn't be C.may not be
選啥,
還有一個辨析的
may be not 與may not be 有區別嗎

解答：

A：can't 「不可能,一定不…」 如He can't know this.
B：mustn't 「不許（表示禁止做某事）」如You mustn't park here.
C：may not be 「或許不…」如He may not know her address.
此句意爲「這本書【不可能】是Lucy的.因爲書的封皮上是Tom的名字.」所以選A.
辨析：①may not be 中的may是情態動詞、用法類似於情態動詞can：後加動詞原形,表否定時直接在情態動詞後面加not +動詞原形.當二者都表示「可能」時、其區別在於may用於肯定句、can用於否定句.所以上面的選擇題中C項意爲「【或許不】」、而不當「不可能」講,因爲may表示「可能」時用於肯定句.
②may be not這樣三個單詞的說法中的may是情態動詞,在句中構成主系表結構,如He may be not a soldier.他【可能不是】軍人.
再問： 你看看這個 http://zhidao.baidu.com/question/165702232.html 是不是真的有這種用法額？
再答： 老外的語言論壇上也有過關於這個問題的帖子~如： ①She may not be at school. => There's a possibility that she is not at school. ②She may be not at school, but ... => True, she is not at school, she's at home, but she's at home studying right now as if she were in school. 又如：Rainy days may be not the most beautiful,but to say love to ... 所以這種說法也可以~ 否定詞not具體放在哪種位置，也要根據說話人想要強調的意思而定~