n.  弧（状）; 弧线；弧形

• arch

  n.  拱〔支撑桥梁或建筑物的弧形结构〕; 〔门、窗上的〕拱

  n.  足弓，足背

  v. （使）拱起，（使）成拱形

  a.  淘气的；调皮的

• the arc of a rainbow  彩虹的弧形

• The Sun moves across the sky in an arc.

  太阳在天空中以弧线方式运行。

• Two rows of trees arched over the driveway. 车道两旁树木交错，形成一个拱顶。

• The dog arched its back. 那条狗弓起了背。

• ‘I think he’s in for a surprise,’ Ian said, in a somewhat arch tone. “我想他很快就会感到惊讶的。”伊恩略带调侃地说道。

• Don't arch your back, keep your spine straight. 别弓着背，挺直脊梁。