Question

---I saw Betty go to Grandpa Zhang’s home just now.

---Yes. She is often seen ______ the old man with his housework.

1. A.
   help
2. B.
   to help
3. C.
   helps
4. D.
   helped

Answer 1

B
警示：此题考查动词不定式在被动语态中的用法。英语中的感官动词，如see，hear，feel，watch，notice等和使役动词如make，let，have等后面的不定式不带to，help后面的动词不定式可以带to，也可以不带to．但用于被动语态时，这些动词后面的不定式必须带to．句中的is seen是被动语态。因此，该题的正确答案是B．例如：
(1)He was made to do the work at once. 他被迫立刻做这项工作。
(2)She was heard to use strong languages. 听说她骂人了。