证券是用来证明()有权取得相应权益的凭证。A.证券发行人 B.证券承销商 C.证券持

抗HDV抗体检测可以反应下列哪一种状况（）

A.是否有HDV血症

B.HDV感染状况

C.HDV复制状况

D.HDV感染时间

E.HDV已经消退

Dear Susan,

I'm very gladly to hear you are coming to visit me the next Friday. Unfortunately, I won't be able to meet you at the airport although I have classes in the afternoon. You won't find difficult to get to the city center. The airport bus leaves every 30 minute and will take you rightly to the Friendship Hotel. My classes will be over by then or I will pick you up there. I will take you together to a hot pot restaurant for dinner and we'll talk with our plan for the weekend over dinner. Having a pleasant trip and see you Friday.

Yours,

Zhang Ming

互联网的体系结构，通常包括互连和互联两个层次。其中前者是物理的，主要由硬件来实现，后者是________，主要由软件来实现。

对于高度分散的、隐蔽的，又不断衍生的犯罪分子，公安机关应当采取的对策是 ( )。

A．“大兵团作战”

B．分散的对案件各个击破，将犯罪分子逐个制裁

C．集中优势兵力重点打击

D．重点在于打击首恶分子

在土的基本物理性质试验中，一般采用（）测定黏性土的密度。

A.环刀法

B.比重法

C.灌水法

D.烘干法