They crossed the frontier at dawn.

他们在黎明时分越过了边境。

The frontier between the two countries is heavily guarded.

两国的边境戒备森严。

They established a new settlement near the frontier.

他们在边境附近建立了一个新的定居点。

The frontier town was bustling with traders and travelers.

边境小镇熙熙攘攘，充满了商人和旅行者。

Early settlers faced many difficulties while peopling the frontier.

早期定居者在边境居住时面临许多困难。

The frontier defence checkpoint is set up at the border line.

边防检查站设在边境线上。

The American frontier was immense.

美国的边境广袤无垠。

The third one is China - Myanmar frontier route.

三是中缅边境之旅.

The Atlantic shore was the original frontier.

大西洋沿岸是最早的边境。

Our car was turned back at the frontier.

我们的汽车在边境处被勒令折返.