根据短文内容，从短文后的选项中选出能填入空白处的最佳选项。选项中的两项为多余选项。
When people get a bad toothache, they often have to eat soft, easily chewed food. ____71___ That’s the conclusion of a zoologist at the Field Museum of Natural History in Chicago and a dentist who works on carnivores (食肉动物).
____72____ Every once in a while, however, a lion will go on a human-eating diet. The most famous such tragedy happened in 1898, when two lions killed and ate 135 railway workers in Kenya.
Examining the preserved skulls of the two big lions, zoologist Bruce Patterson and dentist Ellis Neiburger found that both animals had been suffering from several dental and jaw problems. ____73_____ Canines are pointed teeth that hunting animals use for gripping and piercin
