17 , d . because a force is being applied but it is not moving .
19 . is c .
20 .b .
21 . d .
31 . d .
The metal part of the torch is conductor and the handle maybe the insulattor
Because tropical moist forests are used for agricultural, the thin soil cannot support continuous cropping, while deciduous forests can regrow quickly.
The sun provides light and energy for plants to live and we need plants to breathe
I hope this helps you