帮我看看这几个定语从句题1.It is useful to be able to predict the extent

帮我看看这几个定语从句题
1.It is useful to be able to predict the extent ___which a price change will affect supply and demand.
A from
B with
C to
D for
2.I've never been to Beijing,but it is the place ___
A where I'd like to visit
B I most want to visit
3.It makes no difference ___we will share the office with.
A if
B whether
C Who
4.All___is a continuous supply of the basic necessities of life.
A what is needed
B the thing needed
C that is needed
5.____people spend so much money on their pets ___us a lot.
A That ,is suprised
B How ,are surprised