— Where is my brother, Mum? I haven't seen him this morning.

— He ____ to the library. He will come back soon.[ ]

A. goes

B. is going

C. has gone

D. will go

与宁夏相邻的省区是（）

A.甘肃、青海、陕西

B.甘肃、青海、内蒙古

C.甘肃、陕西、内蒙古