桥拱形跨越河流。

The bridge ___arched over the river.

突然一道闪电呈拱形划过天空，随后传来隆隆的回响。

Suddenly a flash ___arched across the sky, followed by an echoing rumble.

夏日暴雨过后，彩虹拱形跨越地平线。

Rainbows ___arch over the horizon after a summer storm.