In order to find ________ better job, he decided to study ________ second foreign language.[    ]

A. the; a

B. a; a

C. the; the

D. a; the

脉冲多普勒检测卵巢恶性肿瘤流速曲线特点多为（）。

A.中速中阻

B.高速高阻

C.低速高阻

D.低速低阻

E.高速低阻