16、Is oxygen the only gas helps fire burn?
A.it B.which C./ D.that
17、The Second World War millions of people were killed ended in 1945.
A.on which B.where C.in that D.during which
18、The train she was travelling was late.
A.on that B.for which C.on which D.which
19、Winter is the time of year the days are short and nights are long.
A.on which B.that C.when D.where
20、I’ll show you a store you may buy all you need.
A.that, that B.which, that C.where, which D.in which, /16、D 17、D 18、C 19、C 20、D