It was a bright May afternoon along the Maryland coast, and Jonathan Bauer, 51, an expert doctor at a hospital, and his 13-year-old daughter, Ava. were taking full advantage of his professional knowledge to help others. They were driving with the windows down as they headed home on the 1.4-mile-long, two-lane Route 90 bridge, which stretches across the shallow waters of Assa-woman Bay. Suddenly, the calm was disturbed by the high sound of tires.

Not far ahead of them. a black pickup was sliding from one lane to the other. To the Bauers’ horror, it ran into a concrete barrier, turned over the SUV directly ahead of them, and came to rest hanging over the railing(栏杆) of the bridge. Bauer hit the brakes in time to avoid the vehicles in his path.

Bauer stopped the car. “Ava, are you OK?” he asked. She was shaken, but otherwise unhurt.

And then a scream. It came from the pickup. The driver’s door threw open and a man climbed out. He dropped to the ground, then ran to the railing. Bauer ran up beside him. Fhe span pointed down, saying something in Spanish. In the water was a car seat. Fastened to it, a girl, abort two years old. looked terrified, floating on her back, kicking, and splashing and streaming.

Matters quickly went from bad to-frightening when the girl rolled over onto her stomach. Bauer waited for the pickup driver to-do-something, but he didn’t move. Maybe he was in shock.

“Ava!” Bauer shouted, bending to remove his shoes. “Stay by the car!”

He climbed onto the railing and jumped into the water without hesitation.

A moment later the pickup driver pulled Bauer and the little girl ashore and the ambulance arrived.

3 . Crude oil (原油) taken from fields in Alaska's North Slope near Prudhoe Bay is carried by tube to the port of Valdez. From there it is shipped by tanker to the West Coast of the United States. Just after midnight on March24, 1989,the Exxon Valdez, a tanker more than three football fields long, went off course in Prince William Sound near Valdez and hit rocks underwater. About 42 million liters of oil poured out from several slices in the ship, creating the worst escape of oil ever in the U. s. waters.

In 1990，the National Transportation Safety Board NTSB) found the captain of the tanker guilty of drinking before sailing and of leaving the bridge and turning over the ship to an inexperienced and tired third mate. The NTSB ruled that the accident was the result of drinking of the captain, an overworked crew member, and inadequate traffic control by the Coast Guard.

In the early 1970s, conservationists said that a large, damaging oil escape would occur in these dangerous waters containing hidden rocks and frequented by icebergs and violent storms. They urged that Alaskan oil be brought to the lower 48 states by tube over land to reduce potential damage.

Officials of Alyeska, a company formed by the seven oil companies taking oil from Alaska's North Slope, said that a tube would take too long to build and that a large escape of oil was " highly unlikely". They assured Congress that they would be at the scene of any accident within five hours and have enough equipment and trained people to clean up any spill. However, when the S4-ilion Valdez leak occurred, Alyeska and Exxon officials did too little too late.

In the early 1970s, Secretary of the Interior Rogers Morton told Congress that all oil tankers using Alaskan waters would have double hulls( 船体). Later, under pressure from oil companies, the requirement was dropped. After the disaster,the oil industry had much to answer for. The accident led to an international push for double-hulled oil tankers.What if the Exxon Valdez had a double hull?

4 . Time flies, but the tracks of time remain in books and museums. This is what made a recent tragedy in Brazil even more terrible.

On Sept.2, a big fire ripped through the National Museum of Brazil. “ Two hundred years of work, research and knowledge were lost, ” Brazilian President Michel Temer wrote on Twitter after the fire. “It's a sad day for all Brazilians.”

Most of the 20 million pieces of history are believed to have been destroyed. Only as little as 10 percent of the collection may have survived, Time reported. Among all the items, there were Egyptian mummies, the bones of uniquely Brazilian creatures such as the long－necked dinosaur Maxakalisaurus, and an 11,500－year－old skull called Luzia, which was considered one of South America's oldest human fossils.

Besides these, Brazil's indigenous(本土的，土著的) knowledge also suffered. The museum housed world－famous collections of indigenous objects, as well as many audio recordings of local languages from all over Brazil. Some of these recordings, now lost, were of languages that are no longer spoken.

“The tragedy this Sunday is a sort of national suicide, a crime against our past and future generations,” Bernard Mello Franco, one of Brazil's best－known columnists, wrote on the O Globo newspaper site.

The cause of the fire is still unknown, as BBC News reported on Sept. 3. After the fire burned out, crowds protested outside the museum to show their anger at the loss of the irreplaceable items of historical value.

According to Emilio Bruna, an ecologist at the University of Florida, museums are living, breathing stores of who we are and where we've come from, and the world around us.

Just as underwater grass floats on the surface if it loses its roots, a nation is lost without its memories. The fire at the National Museum of Brazil teaches the world an important lesson: We should never neglect history.