There's a feeling in me ________ we'll never know what a UFO is－not ever．

A．that

B．which

C．of which

D．what

There is a new problem involved in the popularity of private cars ________ road conditions need ________．

A．that; to be improved

B．which; to be improved

C．where; improving

D．when; improving

Along with the letter was his promise ________ he would visit me this coming Christmas．

A．which

B．that

C．what

D．whether

It makes no difference ________ he comes or not．

A．if

B．that

C．when

D．whether

The news ________ Lincoln was murdered filled their heart with deep sorrow．

A．which

B．that

C．about that

D．in which

Have you any idea ________?

A．how soon they will arrive

B．how fast will they arrive

C．how quick they will arrive

D．how will they arrive

They have no idea at all________．

A．where he has gone

B．which place he has gone

C．where did he go

D．where has he gone

I have no idea ________ he will come back．

A．where

B．when

C．what

D．that

He made a promise ________ he would help me．

A．what

B．when

C．that

D．which

The fact ________ he didn't see Lao Li yesterday is true．

A．which

B．that

C．when

D．what