In this task, you're given an article and an answer. Your task is to generate the fill-in-the-blank question for this answer based on the given article. The blanks are always at the end of the question, and can be filled with more than one word or phrase.

Article: The earthquake that shook Japan with historic strength on March 11th, 2011 created a _ wave ten meters high. The water washed away boats, cars and houses in coastal areas north of Tokyo. It also led to tsunami warnings across the Pacific. Scientists recorded the magnitude of the earthquake at 8.9.The United States Geological Survey says it was the fifth largest earthquake since nineteen hundred. The largest, with a 9.5 magnitude, shook Chile in nineteen sixty. The quake struck near the east coast of Honshu, Japan's main island. It was centered under the sea about one hundred thirty kilometers east of Sendai.The tsunami washed away whole neighborhoods in Sendai. So far (April 4th), the tsunami has taken 12, 0009 people's life away. Now Japanese are all trying to rebuild their hometown, but there are too many difficulties. The first, Japan is the world's third largest importer of oil. The shortage of oil makes it almost impossible to carry the food, medicine and water to the quake area by cars. The second, the Fukushima nuclear power station was damaged by the March eleventh earthquake and tsunami. The extent of the problems is still not clear. Japan's nuclear crisis may mean greater need of imported food.
Answer: Japan
The largest earthquake happened in _ .

Article: I just finished the household chores for the night and was preparing to go to bed, when I heard a noise in the front of the house. I opened the door to the front room and to my surprise, Santa himself stepped out from behind the Christmas tree. He placed his finger over his mouth so I would not cry out. "What are you doing?" I started to ask. The words choked up in my throat, and I saw he had tears in his eyes. His usual jolly manner was gone. Gone was the eager, boisterous soul we all know. He then answered me with a simple statement"TEACH THE CHILDREN!" I was puzzled; what did he mean? Santa then reached in his bag and pulled out a FIR TREE ."Teach the children that the pure green color of the stately fir tree remains green all year round,describing the everlasting hope of mankind,all the needles point heavenward, making it a symbol of man's thoughts turning toward heaven." He again reached into his bag and pulled out a brilliant STAR. "Teach the children that the star was the heavenly sign of promises long ago. God promised a savior for the world, and the star was the sign of fulfillment of his promise." He then reached into his bag and pulled out a CANDLE. "Teach the children that the candle symbolizes that Christ is the light of the world, and when we see this great light we are reminded of he who displaces the darkness." Suddenly I heard a soft twinkling sound, and from his bag he pulled out a BELL. "Teach the children that as the lost sheep are found by the sound of the bell, it should ring mankind to the fold. The bell symbolizes guidance and return." Santa looked back and was pleased. I saw that the _ was back in his eyes. He said, "Remember, teach the children the true meaning of Christmas and do not put me in the center, for I am but an humble servant of the one that is, and I bow down to worship HIM, our LORD, our GOD."
Answer: he heard something unusual
Author opened the door when he was going to sleep because _ .

Article: Since people first sent rockets into space in the 1950s, we have been leaving behind all sorts of things. Some of them, like the camera, were lost by astronauts while they did work outside their spaceship. But much of the space junk is made up of little pieces of things that were once bigger objects, until they struck each other and broke apart. Some things we send into space fall back toward the earth and burn up in the atmosphere. But larger pieces sometimes survive the extreme heat and hit the ground or the ocean at great speeds. So there is always concern that something may fall from the sky and do some harm. But space junk falling on housetops is not the biggest worry. Scientists are concerned about what happens when an empty rocket strikes another while orbiting the earth. Two big things become many smaller things. They then hit other things. The pieces get smaller and smaller until they form a cloud of junk that blocks the path of future space vehicles. So what can be done to clean up the space around our planet? Marco Castronuovo, an Italian researcher, talks about sending a satellite into space that would get very close to some of the larger pieces of space junk. The satellite would connect a small rocket to the useless object. When the rocket explodes, it pushes the junk into a lower and slower orbit, nearer the earth. After a time, the junk burns up in the atmosphere. Mr. Castronuovo has proposed using a number of small satellites with robotic arms. One arm would catch the space junk, and another arm would connect the rocket. He imagines that each satellite would jump from one large piece of junk to another. He thinks this method could destroy about ten large objects each year. Scientists have been concerned about space junk for many years. Right now, the costs of the clean-up have been too great. Mr. Castronuovo says his system could be put in place for a much more reasonable amount of money.
Answer: returns to the earth piece by piece
Much of the space junk _ .