Gerund or To + Verb
Recently I`ve come across such a sentence "All she does is sit in her wheel chair and watch us". Is the usage of just simple verbs "sit" and "watch" correct here? I thought the gerund of the verbs "sit" and "watch" should be used here, or another variant - the verbs "sit" and "watch" with particle "to"

Question

Gerund or To + Verb
Recently I`ve come across such a sentence "All she does is sit in her wheel chair and watch us". Is the usage of just simple verbs "sit" and "watch" correct here? I thought the gerund of the verbs "sit" and "watch" should be used here, or another variant - the verbs  "sit" and "watch" with particle "to"

Answer

The key is in the auxiliary verb, "does". So you use the present simple.
- "All she does is sit in her wheel chair and watch us." What does she do? She sits in her chair and watches us.

You can use the participle form in present continuous (not the gerund) if you change the first part:
- "All she's doing is sitting in her wheel chair and watching us."

You can use a gerund if the verb allows it. For example, we use gerunds with "enjoy".
- "All she enjoys doing is sitting in her wheel chair and watching us."

Using the infinitive is certainly possible. We'll use a suitable verb, such as "desire".
- "All she desires is to sit in her wheel chair and watch us."  We don't use "to watch" because the second "to" is redundant.

Answer

No, that's right. This sentence implies it's something she does all the time. If it were "sitting and watching" it would sound like it's happening right now. "she's sitting in her wheelchair and watching us". "To" would never be used in this scenario either. "To" would imply doing something "in order to". Like a purpose.