What is the function of the modal in the following sentence? You must show your passport when you travel outside of the country.

#7

#11

Birds and many theropod dinosaurs have hollow bones that are strong, but light; have feathers; S-shaped necks; have a wishbone (or furcula). All these similarities are taken as evidence of common ancestry.

Rapidly changing salinity with depth is called the ________.

The oldest fossil remains of Homo sapiens found so far date from at least A) 6 million years ago. B) 1.6 million years ago. C) 180,000 years ago. D) 60,000 years ago. E) 16,000 years ago.  

#6

With which of the following statements would a biologist be most inclined to agree? A) Humans and other apes represent divergent lines of evolution from a common ancestor. B) Humans represent the pinnacle of evolution and have escaped from being affected by natural selection. C) Humans evolved from chimpanzees. D) Humans and other apes are the result of disruptive selection in a species of chimpanzee.

According to the best available evidence, which of these hominin traits occurred before the others? A) tool use B) increased brain size C) symbolic thought D) language E) bipedalism

Primate evolution and behavior, such as hunting skills, have been directed in part by the development of depth perception. What anatomical change made depth perception possible? A) a larger brain B) the formation of compound eyes C) movement of the eyes to the front of the head D) diurnal activity