用荧光染料标记的抗体处理细胞后在荧光显微镜下对细胞中特殊分子进行定位属于（）

A.放射自显影技术

B.免疫荧光显微镜技术

C.免疫电镜技术

D.液相杂交技术

E.原位杂交技术

On his way to the airport, it ________ him all of a sudden that he had forgotten her birthday. [      ]

A. hit  

B. knocked  

C. occurred  

D. beat