As things stand, the biggest unknown is the track surface.

照目前情况来看，最大的未知情况是赛道的表面。

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If the track surface skid pollution starts, oil should be clear;

若轨道面有油污造成启动时打滑，应清楚油污；

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The only question remaining is whether the light will reflect from the track surface if it rains.

遗留下的仅有的一个问题是如果下雨，灯光会不会经赛道表面反射。

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"The track surface will make it tricky, " said Hamilton, who claimed his maiden Grand Prix victory in Montreal from pole in 2007.

BBC: Hamilton takes Canadian GP pole

C. (AP) Charlotte Motor Speedway said 10 fans were injured Sunday at the Coca-Cola 600 and three of them were taken to the hospital after a nylon rope supporting a Fox Sports overhead television camera fell from the grandstands and landed on the track surface.

NPR: 10 Fans Injured When TV Cable Falls On Race Track

Three groups keep track of global surface temperatures with records that go back more than a century: NOAA, NASA and the British meteorology office.

NPR: World Warm Last Year, But Not Like Record US Heat