1.Yes,it is.
2.I/We need good shoes,clothes and a backpack./ They are good shoes,clothes and a backpack./
Good shoes,clothes and a backpack.
3.I/We can hike in the mountains,in a forest,along a river or in the city.
4.There are three./Three.
5.I/We shouldn't forget safety./It's safety./ Safety.
(答案不唯一)