Look,the duck___.A.swim B.swims C.is swimming

Look,the duck___.A.swim B.swims C.is swimming
I can't find my pen.I am___it.A.looking at B.looking for C.looking out
The boy in the red hat likes summer.(对in the red hat提问）
____ ____likes summer?
She is looking for shells,(改为复数句）
____ ____ ____for shells.