Cloze Exercise Generator

Basics In 1990, the Italian government 1 Select... stabilizeprojectedstumpedurgencyenlistedcrisis top engineers to 2 Select... stabilizeprojectedstumpedurgencyenlistedcrisis Pisa's famous Leaning Tower. There'd been many attempts to right the tower during its 800 year history, but this team's computer models revealed the 3 Select... stabilizeprojectedstumpedurgencyenlistedcrisis of their situation. They 4 Select... stabilizeprojectedstumpedurgencyenlistedcrisis the tower would topple if it reached an angle of 5.44 degrees--- and it was currently leaning at 5.5. No one knew how the tower was still standing, but the 5 Select... stabilizeprojectedstumpedurgencyenlistedcrisis was clear: they had to solve a problem that 6 Select... stabilizeprojectedstumpedurgencyenlistedcrisis centuries of engineers, and they needed to do it fast.

To understand their situation, it's helpful to understand why the tower 7 Select... pilescounteractedembellishedbedrocktiltedpillars *in the first place*. In the 12th century, the wealthy maritime republic of Pisa set about turning its cathedral square into a magnificent landmark. Workers 8 Select... pilescounteractedembellishedbedrocktiltedpillars and enlarged the existing church, and added a massive domed baptistry to the plaza. In 1173, construction began on a free-standing campanile, or bell tower. The engineers and architects of the time were *masters of their craft*. But for all their engineering knowledge, they knew far less about the ground they stood on. Pisa's name comes from a Greek word for "marshy land," which perfectly describes the clay, mud, and wet sand below the city's surface. Ancient Romans 9 Select... pilescounteractedembellishedbedrocktiltedpillars similar conditions with massive stone 10 Select... pilescounteractedembellishedbedrocktiltedpillars called 11 Select... pilescounteractedembellishedbedrocktiltedpillars which rest on Earth's stable 12 Select... pilescounteractedembellishedbedrocktiltedpillars . However, the tower's architects believed a three-meter foundation *would suffice* for their relatively short structure. Unfortunately for them, less than five years later, the tower's southern side was already underground.

Such a shifting foundation would normally have been a fatal 13 Select... compensatedminorflawprolongedpressure . If workers added more weight, the 14 Select... compensatedminorflawprolongedpressure from upper stories would sink the structure and fatally increase the lean. But construction halted at the fourth story for nearly a century as Pisa descended into 15 Select... compensatedminorflawprolongedpressure warfare. This long pause allowed the soil to settle, and when construction began again in 1272, the foundation was on slightly more *stable footing*. Under the direction of architect Giovanni di Simone, workers 16 Select... compensatedminorflawprolongedpressure for the tower's 17 Select... compensatedminorflawprolongedpressure tilt by making the next few floors taller on the southern side. But the weight of the extra masonry made that side sink even deeper. By the time they completed the seventh floor and bell chamber, the angle of the tilt was 1.6 degrees.

For centuries, engineers tried numerous 18 Select... dugstrategiesinjectedbasesunkenworsened *to address* the lean. In 1838, they 19 Select... dugstrategiesinjectedbasesunkenworsened a walkway around the 20 Select... dugstrategiesinjectedbasesunkenworsened to examine the 21 Select... dugstrategiesinjectedbasesunkenworsened foundation. But removing the supporting sand only 22 Select... dugstrategiesinjectedbasesunkenworsened the tilt. In 1935, the Italian Corps of Engineers 23 Select... dugstrategiesinjectedbasesunkenworsened mortar to strengthen the base. However, the mortar wasn't *evenly distributed* throughout the foundation, resulting in another sudden drop.

All these failed attempts, along with the ever-sinking foundation, moved the tower closer to its 24 Select... compositiondevisepinpointtipping point . And without *definitive knowledge* of the soil 25 Select... compositiondevisepinpointtipping point , engineers couldn't 26 Select... compositiondevisepinpointtipping point the tower's fatal angle or 27 Select... compositiondevisepinpointtipping point a way to stop its fall.

In the years following WWII, researchers developed tests to identify those missing 28 Select... trajectoryexcavationdiagonalvariables . And in the 1970's, engineers calculated the curved tower's center of gravity. With this data and new computing technology, engineers could model how stiff the soil was, the tower's 29 Select... trajectoryexcavationdiagonalvariables , and the exact amount of 30 Select... trajectoryexcavationdiagonalvariables needed for the tower to remain standing. In 1992, the team drilled 31 Select... trajectoryexcavationdiagonalvariables tunnels to remove 38 cubic meters of soil from under the tower's north end.

Then, they temporarily 32 Select... featurecounterbalancedanchoringstable the structure with 600 tons of lead ingots before 33 Select... featurecounterbalancedanchoringstable the base with steel cables. More than six centuries after its construction, the tower was finally straightened... to a tilt of about four degrees. No one wanted the tower to fall, but they also didn't want to lose the landmark's most famous 34 Select... featurecounterbalancedanchoringstable . Today the tower stands at 55-- or 56-- meters tall, and it should remain 35 Select... featurecounterbalancedanchoringstable for at least 300 years as a monument to the beauty of imperfection.