镇患者呼吸困难的特点是

A．深大呼吸

B．呼吸浅慢

C．常伴哮鸣音

D．三凹症阳性

E．咳粉红色泡沫痰

It was in the factory ________ his friend worked ________ he picked up a lot of experience.  [ ]

A. where; where        

B. that; where  

C. that; that        

D. where; that