what引导的感叹句在什么情况下不需要不定冠词?

what引导的感叹句在什么情况下不需要不定冠词?
eg:1.What ( ) exciting news it is!Is ( ) news true?
A.an;the B.an;a C./;the
2.—What ( ) sweet music!Do you know who wrote it?
—Beethoven,I think.
A./ B.a C.an
3.Mary has a bad cold.She has to stay in ( ) bed.
A.a B./ C.the
这些为什么都不要用不定冠词修饰呢?不是说What引导的感叹句修饰名词要用不定冠词吗.