25．In Switzerland, six miles west of Geneva,___________ a collection of laboratory buildings.

A．lie

B．are lying

C．lies

D．lays

直线y₁=-x-2与直线y₂=x+4的交于点（a，b），当x＞a时，y₁与y₂的大小关系是：y₁______ y₂（填“＜”或“＞”）．