“数控机床自动编程”课程项目实训报告

“数控机床自动编程”课程项目实训报告

 “数控机床自动编程”课程项目实训报告

“数控机床自动编程”课程项目实训报告

“数控机床自动编程”课程项目实训报告

“数控机床自动编程”课程项目实训报告

“数控机床自动编程”课程项目实训报告

“数控机床自动编程”课程项目实训报告

“数控机床自动编程”课程项目实训报告

“数控机床自动编程”课程项目实训报告

 

第二篇：时事新闻摘抄：'Black Beauty' meteorite reveals secrets of Mars' surface

'Black Beauty' meteorite reveals secrets of Mars' surface

A new study claims a recently discovered meteorite is a chunk of Martian crust that is like nothing else ever discovered on Earth.

The meteorite, known as NWA 7034, weighs just 11 ounces. It was discovered in the Moroccan desert in 2011 and eventually sold to a collector in the U.S.

According to the study by researchers from Brown University and the University of New Mexico, the meteorite, known as "Black Beauty," is about 4.4 billion years old.

When researchers first examined the rock, its chemical makeup confirmed it was indeed from Mars, but it was completely different from any sample ever discovered before.

The majority of the samples from Mars' surface are made from cooled volcanic material. Black Beauty, however, is made up of small fragments of different rocks all welded together - known as a breccia rock.

The planet has more than 400,000 impact craters of at least 1 km in diameter. Impacts of that magnitude are known to cause those brecciated rocks, leading researchers to believe this rock would be characteristic of much of the Red Planet's surface.

"If you went to Mars and picked up a chunk of crust, you'd expect it to be heavily beat up, battered, broken apart and put back together."

The study was published in the journal Icarus.