题目内容：

Over seven months have passed since Panamanian officials launched an expansion of the world famous Panama Canal. Officials agreed to the expansion so that many of the world’s largest cargo ships (货船) could easily pass through the canal. Yet the $ 5.25-billion project has problems. It says ships still continue to rub against the canal’s walls and wear out its defenses designed to protect both shipping and the waterway.

A dangerous system

The canal links two oceans-the Atlantic and the Pacific-through a system of locks (船闸). The locks are like steps. They raise and lower ships from one part of the waterway to another on their trip from ocean to ocean.

With the old locks, which are still in use, large ships would be tied to powerful engines on both sides. These engines help to keep the ships in the center of the canal. In the new locks, the ships are tied to tugboats (拖船). One tugboat is tied to the front of the ship, with the other tied to the back. These boats then guide the ships through the canal.

At first, pilots of the cargo ships and tugboat operators would sometimes try to rub the boats against the canal walls as a way to keep the ships straight. But this caused damage to rubber padding (垫料) lining the walls.

Not enough training

Even before the expanded canal opened in June 2016, tugboat operators had expressed concern about the new system. Many asked for more training. The fears and dangers remain, although the boats are going through.

The Panama Canal Authority reports that, between June 2016 and January 2017, there were only 15 incidents that resulted in damage to locks or ships. That represents about 2 percent of the 700 times ships that have sailed through the expanded canal.

Pilots have argued they should be replaced with a system of floating bumpers (减震) like those used in some European locks. Officials say they plan to continue operating with the current system of defenses, but changes could happen in the future.

1.What is the difference between the new locks and the old ones?

A. The old locks don’t need rubber padding as defenses.

B. The new locks need tugboats tied to both sides of the ships.

C. The new locks are easier for the largest ships to pass through the canal.

D. The old locks need powerful engines to drag the ships through the canal.

2.What is the Panama Canal Authority’s attitude towards the expanded canal?

A. Cautious.    B. Critical.

C. Positive.    D. Doubtful.

3.What can we learn about the current system of defenses?

A. No ships shall rub against the canal walls to protect it.

B. Nothing will be done at present to improve it.

C. More training will be given to pilots for it.

D. A new system will replace it.