骆驼商队穿越沙漠时互相照应。

The ___caravans of camels help each other when crossing the desert.

许多退休夫妇喜欢开着房车周游全国。

Many retired couples enjoy traveling across the country in their ___caravans.

沙漠中有一队骆驼排成一列缓慢前行。

A ___caravan of camels was moving slowly across the desert.