There are some things humans can go without. We can lose a kidney (肾)or a lung, an arm or two and still live perfectly well. But some fish put us to shame. They can get by without stomachs.
One such fish is the stout longtom（尖嘴魚 ）. The group it belongs to carries a more appropriate name: the needlefish. All needlefish lack stomachs. Their ancestors had them, but later they were lost.
The stout longtom can reach 1.3 meters in length, and lives near the sea surface. Like all needlefish, it can jump out of the water to escape its enemies. Tropical(热带) fishermen are sometimes injured by needlefish. In 1977, a 10-year-old Hawaiian boy was killed when a needlefish jumped through his brain. The longtom eats smaller fish. Its teeth are not good at cutting fish into pieces, so it swallows fish whole.
Ryan Day from Australia and his colleagues wanted to know how the longtom digests its meaty meals without a stomach, so they ran some chemical tests about the fish.
Day’s results show that the longtom can consume food without the help of a stomach. It uses a special material called trypsin（胰岛素） that can break down proteins without acid — although the approach is less efficient than using a stomach.
Because it’s a meat-eating animal, the longtom gets a lot of protein in its food, so it can afford this slightly less efficient system for absorbing it. Two plant-eating fish that Day studies actually had higher levels of trypsin in their body, as their food was low in protein.
Day thinks that the longtom and its stomachless relatives might actually have arrived at an energy-saving solution. He says that although the stomach is critical to many kinds of animal, the organ is “a fairly expensive organ to run”. This perhaps explains why some animals have got rid of theirs.
小题1:What does the underlined phrase “get by” mean?
A．Live.
B．Fight.
C．Hunt.
D．Recover.小题2:Ryan Day ran the chemical tests in order to find out how the longtom ______.
A．catches smaller fish in the water
B．can jump so high to escape its enemies
C．digests the smaller fish in its body
D．uses acid to break down the protein小题3:What plays a key role in the longtom’s digestion process?
A．Acid
B．Trypsin.
C．The stomach.
D．Protein in its body.小题4:Ryan Day’s results show that ______.
A．the longtom often waste energy
B．the longtom can make acid easily
C．the longtom’s high-protein food helps its unique way of consuming food.
D．meat-eating fish have higher levels of trypsin in their bodies than plant-eating fish
35mmol/L。