京张高铁轨道贯通

Massive machines require engineering extremes. The massive man-made satellite, commonly known as the International Space Station, hurtling around the Earth at 27,600 km an hour, has been a temporary home for humans for the last 20 years. The biggest land vehicle on earth, a bucket excavator titled Bagger 293, that can move 240,000 cubic meters of dirt each day. Innovation has a...。