F-7型分配阀的紧急部，即紧急放风阀。用于当机车或列车用于紧急制动时，将列车管的压力

The idea has been in my mind for quite a long time that we ourselves are actually responsible for ________ happens in our life.[ ]

A．whichever  

B．however

C．whenever  

D．whatever

Please tell me __________ our teacher will give us a test next week.[ ]

A. if

B. that

C. how

D. that if

与穿破硬膜外血管及注射空气有关（）

A.空气栓塞

B.硬膜外血肿

C.硬膜外脓肿

D.全脊髓麻醉

E.刺破胸膜

F.脊神经根损伤

What is the main topic of the talk

A．Jefferson’s views about commercialized agriculture.

B．International trade in the nineteenth century.

C．Improvements in farm machinery in the United States.

D．Farmers’ loss of independence.

下述选项中，不是二尖瓣关闭不全体征的是：（）

A.心尖区全收缩期高调吹风样杂音

B.杂音向左腋下或背部传导

C.第一心音增强

D.常有第二心音分裂

E.重度关闭不全时可出现心尖部舒张中期杂音