The twins, Who       their homework, were allowed to play badminton on the playground.

A．will finish

B．finish

C．have finished

D．had finished

某青年男性，跑步时摔倒，左膝部着地，伤后感到左膝部剧烈疼痛，但仍然能够行走。被送往医院检查，到达医院时膝部肿胀，检查：膝关节肿胀，浮髌试验阳性，髌骨前方有空虚感。

首先应当做哪项检查（）

A.心电图

B.超声波

C.X线片

D.CT

E.MRI