30． In order to solve the problem of water shortage，we' have to________．

a． make use of sea water on the earth

b． save as much fresh water as possible

c． reuse the water from large cities

d． stop people from，using water

e． only use the 3% of the water on the earth

A．a and e

B．a，b and c

C．b，c and d

D．a，b and d

[单选题]The harder Itried, _____ it seemed to solve that math problem.A.the impossi

[单选题]The harder Itried, _____it seemed to solve that math problem.A.the impossib

It ____________ be the only way to solve the problem.There are other choices.（ ）

[单选题]The most [crucial]issue at present is how to solve the problem of food safe

[单选题]The most [crucial]issue at present is how to solve the problem of food safe

[单选题]The most [crucial]issue at present is how to solve the problem of food safe

Watching the TV program on children, I ___ a good idea to solve the problem.A. c

______ how to solve the mathematics problem, Stephanie asked her teacher for hel

[单选题]This problem is _____his ability and I don’t think he can solve it.A.ToB.in

[单选题]The game requiresus to find out two [simple] but effective ways to solve th