`18.` Will they reduce electricity to save money`?`

`→` Will electricity be reduced to save money`?`

`19.` They will build a hydro power station in this area next year.

`→` A hydropower station will be built in this area next year.

Cấu trúc tương lai đơn bị động: 

`(+)` S `+` will be `+` `P.P` `+` by O

`(-)` `S` `+` won't be `+` `P.P` `+` by O

`(?)` Will `+` `S` `+` be `+` `P.P` `+` by O`?`

reduce - reduced (động từ có quy tắc)

build - built (động từ bất quy tắc)

`18.` Will electricity be reduced to save money?

*Động từ "reduce" `->` reduced

`19.` A hydro power station will be built in this area next year.

*Động từ "build" `->` built

* `=>` Cấu trúc câu bị động (Tương lai đơn):

`(+)` S + will be + V3(ed/BQT) + (by O).

`(-)` S + will + not + be + V3(ed/BQT) + (by O).

`(?)` Will + S + be + V3(ed/BQT) + (by O)?