my father is looking forward to( )his friend from Beijing,应该填什么,为什么

很高兴为你解答.
My father is looking forward to seeing/ visiting his friend from Beijing
我爸爸盼望去见见/拜访他来自北京的朋友.
解析：look forward to doing 盼望做.,to是介词to,后面接doing.我知道look forward to doing 盼望做....，但我想知道为什么填seeing，而不填looking at，麻烦帮助我一下see 强调看的结果，look at 强调一时的动作。那为什么不填lookinglook 是不及物动词，后面接宾语 his friend ，需添加介词at。