John said he’d been working in the office for an hour, ________ was true．

he

this

which

who

The man ________ is shaking hands with my father is manager．

whom

whose

who

/

He has a good knowledge of electricity, ________ helps him a lot in his work．

that

who

when

which

The clock is that ________ tells us time．

which

that

/

it

Who is the person ________ you knocked down just now?

that

which

whose

who

It’s a book ________ will help you a lot．

what

that

whose

/

The only thing ________ you can do is to leave quietly．

that

which

what

it

The man to ________ Tom is speaking is my teacher．

who

whom

whose

that

Where is the pencil ________ I wrote just now?

which

that

in which

with which

He lives in an old house ________ was built 50 years ago．

what

/

which

where