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Which of the following statements best summarizes the main idea of this passage？

A. Hitting the ball to produce different sounds is not an easy matter.
B. The sound of the bat may give fielders more chances to catch the ball.
C. Aluminum bats are inferior to the wooden ones.
D. The study of Robert Adair shocks the Acoustical Society of America.

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Which of the following statement is NOT TRUE according to the passage？

A. If a baseball fielder cannot tell the distance a ball is going to travel by listening to the crack of the bat, they may lose the chance of catching it.
B. If a fielder relies purely upon sound information, the ball may have traveled too far for him to reach it in time.
C. The sound hit on the ball could mean a difference in running distance of as much as 30 meters.
D. If the ball do not hit on the sweet spot, the ball cannot travel as far as possible.

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Following programmed instructions from flight controllers, the six-wheel rover made several short turns and moved forward about six feet. It stopped within inches of the pyramid-shaped rock, about the size of a football. It was the vehicle's second maneuver on the Martian surface since landing there on Jan. 3.
Scientists at the Jet Propulsion Laboratory in Pasadena, Calif., said they did not expect results of the first rock examination until early today. But they were already both pleased and puzzled over the soil test results.
"We're starting to put together a picture of what the soil at Gusev is really like," Dr. Steven W. Squyres of Cornell, the principal scientist of the mission, said at a news conference in Pasadena. He was referring to the Spirit's landing site in Gusev crater, near the Martian equator. Two of the Spirit's main science instruments, the M6ssbauer spectrometer and the alpha particle X-ray spectrometer, made a close examination of soil near the landing base.
German scientists in charge of the studies reported that X-rays emitted by the surface soil indicated a chemical composition mainly of silicon and iron, with smaller amounts of sulfur, chlorine and argon. Argon is a noble gas that is part of the Martian atmosphere. Previous Martian sites visited by landing craft also contained significant amounts of sulfur and chlorine.
Other members of the project's science team said the M6ssbauer spectrometer found considerable amounts of the mineral olivine in the soil. Olivine, which contains oxygen, iron and magnesium, is often found in volcanic rocks. The Martian soil may resemble the volcanic soil of Hawaii.
"One possibility is that this soil is simply ground-up lava," Dr. Squyres said. "That would surprise me, but it's entirely possible that beneath .those grains there is solid rock and we are detecting some of that solid rock, not the s0il."
Another property of the soil perplexed geologists. The fine grains of the Gusev surface seem to stick together in dry clumps. Geologists suspected static electricity as the clinging force. If so, they said, the soil should collapse and flatten out when the M6ssbauer spectrometer pressed against the ground. Nothing collapsed, leading Dr. Squyres to ask what force was. responsible for holding them together.
How many pieces of equipment is the robotic rover Spirit, armed with and what are their names？

A. Two. They are the mechanical arm and the microscopic camera.
B. Three. They are the two science instruments and a microscopic camera.
C. Four. They are the two science instruments, a microscopic camera and the flight controller.
D. Five. They are the two science instruments, the two flight controllers and a microscopic camera and the flight controller.

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"But they were already both ,pleased and puzzled over the soil test results" in Para. 3 can best be used to mean ______.

A. they felt both happy and satisfactory over the test results
B. they didn't expect to find the wonderful results
C. they wanted very much to do more research over the rocks
D. they were glad to see the results but they can't explain them

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German scientists in charge of the studies ______.

A. thought that the surface soil of Mars is mainly composed of silicon and iron, with a bit of sulfur, chlorine and argon
B. doubted if there is any content of silicon and iron, with a bit more of sulfur, chlorine and argon
C. confirmed that the Martian surface emitted X-rays, which indicated the main composition of the Martian soil
D. indicated that the surface soil of Mars has a main chemical composition of silicon and iron

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Which of the following statements best summarizes the main idea of this passage？

A. Hitting the ball to produce different sounds is not an easy matter. B. The sound of the bat may give fielders more chances to catch the ball. C. Aluminum bats are inferior to the wooden ones. D. The study of Robert Adair shocks the Acoustical Society of America.

Which of the following statement is NOT TRUE according to the passage？

"But they were already both ,pleased and puzzled over the soil test results" in Para. 3 can best be used to mean ______.

German scientists in charge of the studies ______.

A. Hitting the ball to produce different sounds is not an easy matter.
B. The sound of the bat may give fielders more chances to catch the ball.
C. Aluminum bats are inferior to the wooden ones.
D. The study of Robert Adair shocks the Acoustical Society of America.