那100美元是我应急备用的钱。

That 100 dollars is my ace in the hole.

youdao

如果你住的地方经常下雪，务必在行驶时带上雪铲、手电(最好装有警戒灯)、毛毯、备用手套等东西以应急。

If you live in region where it snows, do keep the snow shovels to be kept in cars, along with a torch (preferably with a blinker built in), a blanket, spare gloves, etc.

youdao

购物者没钱不能在超市买够东西，只能前往最便利的地方购买紧急时备用应急的食物，如牛奶和鸡蛋。

Shoppers can't afford to load up at the supermarket and are going to the most convenient places to buy emergency food items like milk and eggs.

youdao