Use the drop-down menus to complete each statement. You see lightning before you hear thunder because waves travel faster than waves. Light waves travel the slowest through . Sound waves travel the slowest through and fastest through .

scientists have discovered that hiv does not cause aids by the virus's direct effect on the host's immune cells, but rather through the cells' lethal influence on one another. researchers from the gladstone institutes have revealed that hiv does not cause aids by the virus's

he forelimbs below belong to four species that descended in a direct line from the ancestral mammal shown above. of the four descendants shown, which species most likely appeared earliest in evolutionary history?