She wrote a letter to her father, ________ she made her secret known．

A．which

B．that

C．in which

D．where

China has hundreds of islands, ________ we all know．

A．in which

B．at which

C．of which

D．which

Robert is good at language, ________ we all know．

A．because

B．for

C．as

D．since

Don’t do such things ________ you are not sure about．

A．that

B．which

C．as

D．what

The professor has two sons, ________ are teaching in the same university．

A．neither of them

B．either of them

C．both of them

D．both of whom

The factory ________ I am going to is the place ________ my mother used to work many years ago．

A．where, where

B．where, which

C．which, where

D．that, which

This is one of the means ________ the electric energy is conducted from one place to another．

A．by which

B．by that

C．through which

D．through that

In the dark street, there wasn’t a single person ________ she could turn for help．

A．that

B．who

C．from whom

D．to whom

She heard a terrible noise, ________ brought her heart into her mouth．

A．it

B．which

C．this

D．that

He paid the boy 10 dollars for washing ten windows, most of ________ had not been cleaned for years．

A．these

B．those

C．that

D．which