后备军的英文：
landwehr
reserve

参考例句：

Two infantry divisions were held in reserve.
两个步兵师留作后备军。

Look at that boy, like a real additional soldier of reserve duty.
看这小子，真像一个预备役后备军。

The reserve is called out in the U.S.A. when the Gulf War is impending
海湾战争即将爆发时，美国把后备军召集起来。

As a precaution, the marrow houses a standby force of fully developed white cells
为了预防不测，骨髓中还储存着已经完全成熟的白血球后备军。

landwehr是什么意思：
n. 后备军
reserve是什么意思：
v. 储备，保留；预订；推迟
n. 储备（物）；储藏量；储备金；自然保护区；替补队员；内敛；后备军
adj. 保留的；预备的

reserve decision
推迟判决

For example,hotel reservation,ticket reservation,restaurant reservation and so on.
比如说，旅馆预订，票子预订，餐厅预订等。

They have reserved a box for us in the theatre.
他们在剧院为我们预订了一个包厢。

Do you have the reserved seats yet?
还有可预订的座吗？

RNR (Royal Naval Reserve)
皇家海军后备队