What are two ways floods can be controlled?

One of the ways is to construct dams across rivers that store water so it doesn't spill onto the adjacent land.

Another way is to construct levees, which are lateral walls along a river. The levees confine the rivers to the channels, so the river doesn't spill onto the adjacent land.

Another way is to build a sea wall, revetment, or bulkhead along the coast to keep excessive high tides from spilling onto the adjacent land. Salt marshes also serve to help reduce excessive high tides from spilling onto the adjacent lands.  

the answer to your question is slate

spiders belong to a group of arachnids.

arachnids have the following traits :

they have two body parts.

they have eight legs unlike insects which have 6 legs.

they have no wings.

these traits distinguish them from insects.

the information that antonio is doubting us the statement that spiders differences are as a result of being first to evolve.

this is because the evolution of one species is independent of the other species.