Believe it or not, he was seen upstairs just now. A. to go B. to going C. having
来源：网络
时间：
推荐文章
Believe it or not, he was seen ______upstairs just now.
A. to go B. to going C. having gone D. go
试题答案
A
解析:
see, watch, look at ,feel, notice, observe, listen to, hear 等感官动词（短语）及make, let, have等役使动词后用不带to的不定式作宾补，但这类结构变成被动语态时，to
不可以省略另外，在感官动词后也可用现在分词作宾补，但其意义表示动作正在进行。如：I saw him running after the bus.(动作正进行)