adj.秘密的；偷偷摸摸的
They made a backdoor decision to leave this city. 他們決定秘密地離開這座城市。
The leaders of the two countries held a backdoor meeting yesterday. 昨天兩國(guó)領(lǐng)導(dǎo)人進(jìn)行了秘密的會(huì)談。
