左心衰最早的临床表现是:()
A、劳力性呼吸困难
B、阵发性夜间呼吸困难
C、哮鸣音及吸气性呼吸困难
D、带有哮鸣音的呼气性呼吸困难
E、端坐呼吸
参考答案:B
m是方程x2+x-1=0的根,则式子m3+2m2+2007的值为( )
A.2007
B.2008
C.2009
D.2010
There aren't _____ pictures in the classroom, but there are _____ books.[ ]
A. any, some
B. some, any
C. any, any
D. some, some