1.严谨的（形容词）；2.装甲的（形容词）

1. (adjective) Describing something quite dependable; unchangeable; without flaws.

2. (adjective) Covered with plates of iron.

EXAMPLE 1: The ironclad purchase agreement clearly and definitively outlines the responsibilities of both the buyer and the seller.

这份严谨的采购协议清楚明确地概括了买卖双方的责任。

EXAMPLE 2: The ironclad hulls of nineteenth century warships often deflected cannonballs fired by enemy artillery.

19世纪战舰的装甲船体经常将敌人大炮打来的炮弹挡回。

机灵的（成语）

(IDIOM) Very intelligent.

EXAMPLE: Our accounting consultant may be old but she's sharp as a tack, and in only a few minutes she found a number of errors in our accounts.

我们的会计顾问虽然年老，但是非常机灵，她在几分钟内就发现了账目中的很多错误。