患者，女性，40岁，30min前由汽车上摔下，枕部着地，伤后昏迷未醒，枕正中有挫伤，双瞳孔散大固定，光反射极弱，四肢伸直，双下肢病理征阳性。急输甘露醇500ml后，左瞳孔缩小。进一步的急救措

A．左额开颅清除血肿

B．右额开颅清除血肿

C．左颞肌下减压术

D．右颞肌下减压术

E．枕部开颅清除血肿并减压术

David didn’t give up ______ he had failed in the experiment four times．

A．if

B．while

C．though

D．since