肾窦回声呈
A．高回声
B．中等回声
C．低回声
D．无回声
E．中高回声
参考答案：A
--Excuse me, Where is the nearest hospital?
---GO______ the road, then turn left ____the first turning.
A down in B across on C along at D along across
星形联接中，线电压=（）×相电压；线电流=（）×相电流。
A.2
B.1
C.3
