how tall is she和how tall she is區(qū)別：

　　前者是特殊疑問(wèn)句，后者是名詞性從句。

　　在特殊疑問(wèn)句中，疑問(wèn)詞后面跟的是一般疑問(wèn)句的語(yǔ)序，除了提問(wèn)主語(yǔ)部分的疑問(wèn)句外，如：

　　What's the problem?

　　Where are Robbie and Alexandra?

　　Why didn't they come?

　　在名詞性從句中，特殊疑問(wèn)詞后面跟的就不是一般疑問(wèn)句的語(yǔ)序了，而是陳述句的語(yǔ)序，如：

　　I wonder what the problem is.

　　I don't know where they are.

　　I don't understand why they didn't come.