She told me that she has already gone to the United States four times before she attended that conference.

A．had already been

B．has already been

C．already went

D．was already going

巴黎系统规定，单平面插植最多使用9根放射源，三角形双平面插植最多也使用9根放射源，而正方形排列为（）根放射源。

A.8

B.9

C.10

D.11

E.12