广泛性焦虑症（）
A.发作性病程
B.持续性病程
C.慢性波动性病程
D.病程呈进行性加重
E.病程呈阶梯式进展
参考答案：B
A new survey shows that 54% of Americans do not take prescription medicines _______ though they are important to their health. [ ]
A. as they instruct
B. as were instructed
C. as to be instructed
D. as instructed
2T2T OLSM表示（）
A.传输分集，速率高，
B.传输分集，速率不高，
C.空间复用，速率高，
D.空间复用，速率不高.
