When asked to explain ________ made his lessons so exciting, the teacher kept silent.

A．what it was that

B．that what it was

C．what was it that

D．that what was it

以下关于肾动脉狭窄性高血压的介入治疗方法中，常用的是（）

A.肾动脉内药物灌注术

B.狭窄肾动脉球囊扩张及内支架置入术

C.完全性肾动脉栓塞

D.部分性肾动脉栓塞

E.完全性肾上腺动脉栓塞