gather

The cheapest way to provide water in the dry tropics is through small-scale projects, such as gathering rainfall in depressions

assume

Since people assume that accidents are bound to occur, they want to know how cars can be built better to protect the drivers.

suppose

W: Excuse me, Sir. You are not supposed to be here.This area is for airport staff only.

M: … I didn't note the sign.

ensure

Dale Carnegie suggested as much more than 50 years ago,hard work alone doesn't ensure career advancement.

assure

He was proud of being chosen to participate in the game and he assured us that he would try as hard as possible.

otherwise

Just staying up late can cause increased academic difficulty and attention problems for otherwise healthy, well-functioning kids.