Why does the Leaning Tower of Pisa in Italy lean? It leans because of a mistake. It has leaned almost since the day the tower was built.
In 1173, the people of Pisa, Italy, wanted to build a bell tower. They wanted the tower to be the most beautiful bell tower in all of Italy. The city also needed a bell tower because the church did not have one.
However, there was a problem. As soon as the first floor of the building was finished, the tower started to lean. Builders tried to make the building straight again as they added more floors, but they couldn’t figure out how to make it stop leaning.
It took almost 180 years to finish the tower. Since then, the tower has leaned by another millimeter every year. Today, the Leaning Tower has eight floors and is 54.5 meters tall. By 1990, it was leaning by about 4 meters to one side. It was also slowly sinking into the ground. Many people became worried that it would soon fall apart.
In 1998, repair works began on the tower, and by the end of 2001, it had been moved back by 45 centimeters. The tower will still lean, however, so it will need to be repaired again---in another 200 years.
小题1:why did the people of Pisa want to build the tower?
A．They needed a new church
B．They wanted to build the tallest tower in Tower
C．They needed a bell tower.
D． They wanted to build a leaning tower.小题2:When did the tower begin to lean?
A．from the first day it was built
B．after the first floor was built
C．after the last floor was built
D．180 years after it was built小题3:When was the tower finished?
A．in 1173
B．in 1180
C．in 1353
D．in 1474小题4:Before being repaired,, the tower leaned every year by another _______
A．1 millimeter
B．45 centimeters
C．54.5 millimeters
D．4 meters小题5:Which of the following is NOT true about the tower?
A．It was sinking into the ground
B．People were worried it might fall apart
C．It was repaired between 1990 and 1998.
D．It will need to be repaired again in 200 years.
sin100πt （V）的 正弦交流电源，图中电流表内阻不计．副线圈接入“110V，60W”灯泡一只，且灯光正常发光．下列说法正确的是（ ）
/22 A