No one knows for sure how the ancient Egyptians built the pyramids that rise high above the desert near Cairo. But a new study suggests they used a little rock "n" roll. Long-ago builders could have attached wooden posts to the stones and rolled them across the sand， the scientists say.

People have long puzzled over how the Egyptians moved such massive rocks. And there's no obvious answer. On average， each of the two million big stones in the Great Pyramid at Giza weighed about as much as a large pickup truck. The Egyptians somehow hauled those limestone blocks to the pyramid site from rock quarries a kilometer （0.6 mile） or more away. The leading argument has held that Egyptian workers slid the blocks along slick paths. These would have resembled long Slip "N" Slides - but ones made from desert materials. Many scientists suspect workers first would have put the blocks on sleds. Then they would have dragged them along ramps. To ease the blocks along， workers may have lubricated the ramps either with wet clay or with the fat from cattle.

Evidence from the sand near Giza supports this idea. Researchers found small amounts of fat， as well as chunks of limestone and the remains of ramps. And ancient temples contain drawings that show people using sleds to move giant statues.

However， A physicist at Indiana State University thinks there might have been a simpler way ， he led the new study. The physicist was inspired while watching a television program showing how sleds might have helped with pyramid construction. A square could be turned into a rough sort of wheel by attaching wooden rods to its sides， he realized. That， he notes， should make a block of stone "a lot easier to roll than a square".

So researchers tied three dowel rods to each of four sides of a 30-kilogram limestone or concrete block. That action turned the block's cross-section into a dodecagon， or 12-sided figure. Then they placed the block on the ground， like a spool of thread lying on its side. They wrapped one end of a rope around the block and pulled. The researchers found they could easily roll the block over grass， gravel and hard-packed dirt. They calculated that rolling the block required about as much force as moving it along a slippery path.

The physicist isn't the first scientist to think about rolling blocks to the pyramids. Earlier researchers， however， did not measure the force needed to overcome the friction of the stone rubbing against the sand. In physics， force is a measure of the effort needed to move an object or change its movement.

The physicist hasn't tested his idea on larger blocks， but he thinks rolling has clear advantages over sliding. For instance， workers wouldn't have needed to carry cattle fat or water to lubricate the ramps.

1. Which of the following is NOT the evidence supporting the argument that Egyptian workers slid the blocks of massive stones along slick paths to the pyramid site？ ____.

A. Small amounts of fat found near Giza

B. Chunks of limestone found near Giza

C. The remains of ramps found near Giza

D. Giant statues found near Giza

2. The dominant argument over ancient Egyptians moving massive rocks to the pyramid site is that ____.

A. they used canals to transport the rocks

B. they slid the rocks along slick ramps

C. they rolled the rocks

D. they carried the rocks with horse carriages