(E) greater was coronary disease likely

15. Carnivorous mammals can endure what wold otherwise be lethal levels of body heat because they have a heat-exchange network which kept the brain from getting to hot.

A. which kept

B.that keeps

C.which has kept

D. that has been keeping

E. having kept

18. Unlike the nests of leaf cutters and most other ants,situated underground or in pieces of wood,raider ants make a portable nest by entwining their long legs to form “curtains” of ants that hang from logs or boulders,providing protection for the queen and the colony larvae and pupae

A. the nests of leaf cutters and most other ants

B. the nests of leaf cutters and most other ants,which are

C. leaf cutters and most other ants,whose nests are

D.leaf cutters and most other ants in having nests

E. those of leaf cutters and most other ants with nests