sentence structures

[panicmonger]

You are necessary to do these tasks.
You are obligatory to do these tasks.
You are mandatory to do these tasks.
You are compulsory to do these tasks.
I am voluntary to do these tasks.

Are they all correct & grammatical?

Or do I have to change all of them into the following?

It is necessary/obligatory/mandatory/compulsory for you to do these tasks.
It is voluntary for me to do these tasks.

Thank you & Merry Christmas.

 

[SoothingDave]

"You" are not "mandatory" or "obligatory." The tasks are mandatory or obligatory.

Yes, re-write them.

("You are necessary to do the tasks" means something different. Not that the tasks must be done by "you," but rather that the tasks can not be done without "you.")

 

[sarat_106]

You are necessary to do these tasks.
You are obligatory to do these tasks.
You are mandatory to do these tasks.
You are compulsory to do these tasks.
I am voluntary to do these tasks.

Are they all correct & grammatical?

Or do I have to change all of them into the following?

It is necessary/obligatory/mandatory/compulsory for you to do these tasks.
It is voluntary for me to do these tasks.

Thank you & Merry Christmas.

Here the important point is, you can not use ‘to’ infinitive directly after any adjective. Generally infinitives are used after adjectives which express people’s reactions and feelings. Common subjectexamples are: pleased, glad, surprised, happy, anxious, shocked, afraid etc.

• She was anxious to go home.
• I was surprised to get her letter.
• It is nice to talk to you.

Look at the third example. You can not say “She is nice to talk to you”. • You can use ‘to’ infinitive clauses after adjectives when the subject is impersonal ‘it’.
In the examples, the setence structure will be correct with impersonal subject 'it' and not with a personal pronoun.

 

[lauralie2]

To sum up, the structure is as follows:

• It is obligatory that you do these tasks.
  • That you do these tasks is obligatory.
• It is mandatory that you do these tasks.
  • That you do these tasks is mandatory.
• It is compulsory that you do these tasks.
  • That you do these tasks is compulsory.

• It is important that you volunteer to do these tasks.
  • That you volunteer to do these tasks is important.