There will be a test very soon. The students look like soldiers preparing for battle.
Examples (Wiktionary)
Mandarin
有一天，动物园里的袋鼠“越狱”成功了，动物园的管理员们如临大敌，召开了一个紧急会议，讨论为什么袋鼠会逃跑成功，有一个员工认为是笼子高度太低，而让袋鼠爬走了。
有一天，動物園裏的袋鼠“越獄”成功了，動物園的管理員們如臨大敵，召開了一個緊急會議，討論為什麼袋鼠會逃跑成功，有一個員工認為是籠子高度太低，而讓袋鼠爬走了。
yǒu yī tiān ， dòng wù yuán lǐ de dài shǔ “ yuè yù ” chéng gōng le ， dòng wù yuán de guǎn lǐ yuán men rú lín dà dí ， zhào kāi le yī ge jǐn jí huì yì ， tǎo lùn wèi shén me dài shǔ huì táo pǎo chéng gōng ， yǒu yī ge yuán gōng rèn wéi shì lóng zi gāo dù tài dī ， ér ràng dài shǔ pá zǒu le ．
One day, a kangaroo in the zoo successfully "escaped from prison". The zookeepers kept their guards up and convened for an emergency meeting to discuss why the kangaroo succeeded in escaping. One of the staff members thought that the cage was too short and allowed the kangaroo to crawl out.
Mandarin
大敌当前，他们要联合工农反对敌人；工农觉悟，他们又联合敌人反对工农。
大敵當前，他們要聯合工農反對敵人；工農覺悟，他們又聯合敵人反對工農。
dà dí dāng qián ， tā men yào lián hé gōng nóng fǎn duì dí rén ； gōng nóng jué wù ， tā men yòu lián hé dí rén fǎn duì gōng nóng ．
When confronted by a formidable enemy, they united with the workers and peasants against the enemy, but when the workers and peasants awakened, they turned round to unite with the enemy against the workers and peasants.