We are all looking forward to visiting your country .为什么用这个visiting 动词

我们都期待着访问你的国家.
looking forward to 盼望,期待...sth 或 doing sth.
to在这里不是用作动词不定式,而是用作介词,后跟名词或动名词.
如:
I'm looking forward to it
我盼望着这件事.
We are looking forward to their visit with eager anticipation
我们热切地期待着他们的来访.
The children were eagerly looking forward to the party
孩子们热情地期待着晚会.
The people are looking forward to being delivered from the nasties
人民期待着从不愉快的状况中解脱出来.