PET显像主要采用能发射()的()。
参考答案:正电子;核素及其标记物
-You didn't send me an e-mail last night, did you?
-Sorry. My computer ______________, so I couldn't get online. [ ]
A. broke down
B. broke off
C. broke out
D. broke into
公开发行股票的公司,其财务审计与资产评估工作可以由同一家机构承担。