E.coli can be helpful and harmful at the same time if you know what i mean. E.coli produces a toxin that can be very harmful to people. Also,e.coli is helpful because it help digest your food.
Helpful to humans in the right place; your small intestine. Can be very harmful in the wrong place; your drinking water infected with fecal matter.
If you need help I recommend you type in the specific question you need help with
it can be helpful or harmful
sometimes they are helpful and harmful.
Bacteria can be both harmful and helpful
Sandpaper is both helpful and harmful.
they are helpful not harmful to plants
harmful
Depends on what part of "harmful" or "helpful" you are referring to.
helpful
Helpful
helpful
Harmful bacteria will harm you. Helpful bacteria will help you.