"More harmful" and "most harmful." We would not use the -er and -est suffixes on the -ful which is already a suffix.
what are the danerous or harmful drugs
a synonym for finished is done.
HIV is harmful and dangerous.
estimate
Toss or pitch would be a couple.
It is not harmful but it dangerous.
For harmful, damaging, injurious, detrimental, negative, hurtful, destructive. For dangerous, hazardous, perilous, unpredictable, vulnerable, treacherous
Noxious
very harmful
a synonym may be to stick or apply itself
Cods aren't harmful to humans.