When are you required to use "that" in a sentence?

[Stockmoose16]

How do you know when "that" is required in a sentence?

I.e

I hope you are okay.

I hope THAT you are okay.

OR

A majority of the international journalists surveyed view nuclear power stations as unsafe at present but THAT they will, or could, be made sufficiently safe in the future.

A majority of the international journalists surveyed view nuclear power stations as unsafe at present but they will, or could, be made sufficiently safe in the future.

[Stockmoose16]

Doesn't anyone know the answer to this?

[kiranlegend]

How do you know when "that" is required in a sentence?

I.e

I hope you are okay.

I hope THAT you are okay.

OR

A majority of the international journalists surveyed view nuclear power stations as unsafe at present but THAT they will, or could, be made sufficiently safe in the future.

A majority of the international journalists surveyed view nuclear power stations as unsafe at present but they will, or could, be made sufficiently safe in the future.

for the first one.. in the daily usage it is not incorrect to say i hope you are okay.. but (I am not sure) on gmat 'THAT' is rrequired i guess..

I hope (that) you are okay = I hope that you are okay.. that is perse assumed..

for the second one: later one is the correct one.. but that.. but is already acting as a conjunction..

anyway, more comments will be appreciable:)

[pepeprepa]

Very interesting question, here is what i noticed but I am not fixed at all on "that":

When "that" is subject you cannot delete it.
Ex: This is the book that sold so well.

When "that" is a verb complement you can delete it.
Ex: The man (that) I met is a doctor.
Ex: This is the book (that) I bought in London.