单项选择题

In Boulder, Colo. , a surge of electricity on the power grid can largely go unhoticed. The grid is monitored electronically, so that if there are any sudden rushes or fallen power lines, electricity is automatically rerouted(使改变路线) from one part of the system to another. This pilot project sounds simple enough—maybe even a little obvious. But this new type of technology could have prevented the 2003 blackout that knocked out power to much of the Northeastern United States. On that August day’a few sagging power lines brushed against some trees, and the lines shut down. This set off a domino effect, as ome part of the grid taxed another. The result By the end of that humid evening, 50 million people in eight states and southeastern Canada were left without power.
What will happen if there are fallen power lines in -,in electrically monitored grid