输卵管妊娠的直接证据是：A．子宫内可见妊娠囊 B．宫旁一侧见混合性包块，其内有妊娠囊

A fixed income portfolio manager is evaluating investments in the mortgage market but is concerned about prepayment risk. The security that will most likely minimize prepayment risk is.（）

A. mortgage passthrough security.

B. a portfolio of interest-only mortgage loans.

C. tranche B of a collateralized mortgage obligation.

Oh, the box is too heavy（）

A.What‘s in it?

B.Can I help you to carry it.

C.Whose is it?

D.May I have a try.

下面关于扩展分区和逻辑分区的说法，正确的是（）。

A、一个扩展分区可以划分成为多个逻辑分区

B、一个逻辑分区可以划分成为多个扩展分区

C、扩展分区与逻辑分区是相互独立的

D、必须行建立逻辑分区，才能创建扩展分区

飞机在雨层云中飞行，会出现下列何种现象（）.

A.能见度极差，飞机颠簸严重，有冰雹和雷电

B.能见度较差，连绵的小雨，轻到中度颠簸

C.云中飞行平稳。但能见度恶劣，长时间在云中飞行可产生中度到强烈的积冰