I am quite ______ that the new cosmetics, whether it appears in the form of tablet, capsule, powder or

injection, will _______ through the country among young ladies. [ ]

A. optimistic about; sweep  

B. optimistic ; sweep  

C. pessimistic; spread  

D. pessimistic about; spread

关于塔顶放大器，以下哪些叙述是正确的（）

A.能够提高BTS的接收灵敏度，扩大覆盖范围，

B.改善网络的通话质量，减少误码率.掉话率，

C.降低长距离馈线引入的噪声及干扰，

D.降低手机发射功率，减少对人体辐射.