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)