I am really looking forward _____ to relax with you on this nice island为什么选 to have time

是to having time吧I am really looking forward _____ to relax with you on this nice island.？A.to have had time B. having time C. to have timeD. to having time我想也是BD中的一个，但上网查了，这道题的答案都给是Clook forward to doing sthto是介词，后面自然要跟动名词ing啦，选D选D答案我用了1秒钟，但标准答案给了个C，上网查了其它的出处，还发现是C，这个用了我有20分钟。我也同意选D。就是的，要相信语法，答案也有印错的时候。