800FDCS系统组态中,装置现场使用的MTL温度数采型号为()
A、MTL830
B、MTL831
C、MTL837
D、MTL838
参考答案:B
As the sea ice melts sooner each swimmer,polar bears are forced to come ashore earlier and face food shortages _____ they have stored enough fat to last them through the season.[ ]
A .before
B. unless
C. since
D. until