英语翻译
located at the NASA Rearch Centre in Iowa is a 5,ooo--gallon vat of water and inside the tank is an underwater treadmill designed by Dava Newman,an aerospace engineer.这里面的is 怎么翻译?搞不清楚什么时候翻译成“是”,什么时候翻译成“有”
For 4 years Newman observed scuba divers as they simulated walking on the Moon and on Mars on her underwater moving belt.这里面的as怎么理解