Finite

to V

V-ing

WH

Subject
 

that he is dumb is obvious

to err is human

running a lot  helps you lose weight

what he says is what we'll do

Extraposed
subject

it's sad/a fact that he's so selfish

it's important to study hard

it's nice not having homework

it's not clear what do do

Subject
predicative

his expectation is that we'll help

the plan is to meet her at 8

the hard part is letting go

the question is what to do now

Object
 

I hope that they come

I want to eat more chocolate

I started writing a letter

I don't know what to do

Adjective
complement

I'm sure that they can help us

we're glad to have you with us

she's hopeful of winning the prize

she's unsure of what to do