不定式前有do,后省to

问题描述:

不定式前有do,后省to
the first thing i want to do is _______
a.visit to him b.to visit him c.visiting him d.visited him
我觉得是用visit him,应该省掉to,还是另有玄机?

B 动词不定式作表语,不能用visit him