— Wow! It snowed last night. What a nice world!

— You're right. But it's more difficult to find my missing keys with snow________ the ground.[      ]

A. covered  

B. cover

C. to cover  

D. covering

男，33岁，颈部包块半年余，可随吞咽上下移动，请结合影像学检查，选出最可能的诊断()

A．胸腺瘤

B．淋巴瘤

C．纵隔畸胎瘤

D．淋巴管瘤

E．胸骨后甲状腺肿