“备用”造句

他老是记不起把自己阅读时用的放大镜放在什么地方，所以助手们会随身携带备用的。
He misplaces his reading glasses with such regularity that aides carry extras.

他本该带上一把备用钥匙的。
He could have taken a spare key.

备用罐上写着“高度易燃”。
"Highly inflammable," it says on the spare canister.

• #备用