| 44.A team of scientists has
A.erected a pressure-releasing pipe in the lake
B.identified the gases at the bottom of the lake
C.built a beautiful fountain near the lakes
D.removed all dangerous gases from the lakes
To protect people nearby until all of the pipes are in place.The scientists have installed early warning systems at both lakes.If the gas pressure rises to a dangerous level，computers will set off loud sirens（警报）and bright lights to warn the people in the villages.（45）That way, they will have time to escape from the dangerous gases.
45.What do we learn from the last paragraph?
A.Scientists are planning to install pipes in all crater lakes.
B.Scientists still do not know how to prevent gas explosions.
C.Explosion disasters could be avoided in the future.
D.Warning systems have been set up in the villages nearby.