The clever boy made a hole in the wall, ________ he could see what was going on inside the building.

Do you remember the name of the company ___________?

The teacher set such a difficult problem ________none of us could solve.

The silk road, _______ Marco entered China, was important for the exchange of goods and ideas.

The singer hopes her concert will be like a big party ________ everyone enjoys themselves.

Thomas is the very person     I think is worth making friends with．

Too much fishing may harm fish population to the point________they can’t recover.

-----Is this city _______ he visited the other day?
------No, this is the city ________ he was born.
A, that ,  ,that   B. the one, where   C. the one,  on which   D. that , where

Tom hid himself behind the door, _______ he rushed out to scare his mother.

There are many kinds of birds in Australia, and over 140 species of snakes, ______are extremely dangerous.