You can purchase additional insurance.

你可以购买附加保险。

I bought some new locks as an additional insurance against theft.

我买了新锁具以进一步防止盗窃。

I bought some more locks as an additional insurance against burglary.

我又买了些锁,作为额外的防盗措施.

I bought another safety lock as an additional insurance against thieves.

我又买了一把保险锁,以加强防贼的安全措施.

The seller must provide the buyer, upon request, with the necessary information for procuring any additional insurance.

应买方要求，卖方必须向买方提供额外投保所需的信息。