单词can-t-hit-the-broad-side-of-a-barn
Whenever you have plenty of ammo, you never miss. Whenever you are low on ammo, you can"t hit the broad side of a barn.
你有足够弹药的时候,你百发百中。你缺弹药的时候,连谷仓的宽边那么大的东西都打不中。