e.g. You can ~ meat or fish in salt.

你可以用盐来保存肉或鱼。

(2) 保持；维持

e.g. It is one of the duties of the police to ~ public order

7.sharpen. vt /vi 使变锐利 锋利 、磨快刀

sharpen a pencil with a knife.

Sharpen a knife.

Sharpene stone tools.

n. sharpener 磨快的用具

adj. Sharp 锐利的、陡峭的、激烈的、凛冽的

8．Preserve vt 保存、保护 、保管

The city should take steps to preserve the old temple.

Preserve... from..保护使免于

Oil preserves metal from rust.

Vt.保存 、储藏 , 维持、保护

Preserve fruit in sugar cans.

Preserve one's strength.

9．I'm sorry to interrupt you, but how could they live here?

I'm sorry, but ......

Excuse me , but....

10.We have been excavating layers of ash almost six meters thick, which suggest that they might have kept the fire burning all winter.