Nonnative species are not always a negative factor, they become invasive species .

a.
as soon as they are introduced in an ecosystem
b.
as soon as they leave their original ecosystem
c.
when they start consuming the food meant for the native species
d.
when their presence become economically or environmentally damaging
e.
when they control other species

Grade 91.)the gravitational pull from the moon words).2.) what is the rate of gravitational 3.)if you drop a hammer, is it more likely to drop handle side down, head side down, or equal chance that it will land either way? why? 4.)a car moves 60km east and 90km west.a.) what is the distance the car traveled? b.) what is the car's displacement5.)what is the average velocity of a car that moved 60 km south in 3 hours? 6.) a car starts from rest and acceleration to 60 m/s over a time of 5 seconds. what is the acceleration of the car? 7.)what is the speed of an object at rest?