Generally speaking, _____according to th

A mortgage-backed security has the following characteristics: It was created by pooling a collection of more than a thousand mortgages Not all investors face the same prepayment risk Investors receive three distinct kinds of cash flows Freddie Mac issued the security This security is a(n):（）

A. collateralized mortgage obligation.

B. stripped mortgage-security.

C. mortgage passthrough security.

以下课程理论流派取消了课程问题特殊性的是( )

A．存在主义课程论

B．经验主义课程论

C．学科中心主义课程论

D．社会改造主义课程论

简述脑脊液产生及循环途径。

Elephants have their own way to tell the shape of an object and____it is rough or smooth.[ ]

A.不填                      

B. whether

C. how                     

D. what

关于流行性感冒，以下说法不正确的是（）

A.起病急，潜伏期1～3天全身症状较重

B.流感病毒为RNA病毒

C.临床分为单纯型、胃肠型、肺炎型和中毒型

D.鼻咽部症状较重

E.白细胞总数不高或减低