Why is it so important for astronauts to make sure that they keep things clean in outer space?

Northeastern china, north korea, northern japan containing coniferous forests, temperate grasslands, and agriculture, are all part of what climate zone? a. tropical desertb. desertc. humid subtropicald. humid continental

The meseta in spain is a a. navigable river b. castle c. coastal plain d. plateau

To solve this system of equations by elimination, what operation could be used to eliminate the y-variable and find the value of x? 6x + 5y = 2 4x + 2y = 8 a) subtract 2 times the second equation from 3 times the first equation b) subtract 3 times the second equation from 2 times the first equation c) subtract 5 times the second equation from 2 times the first equation d) subtract 2 times the second equation from 5 times the first equation