2 sentences

1. 突击队在敌军防线上打开了一个突破口。

   tū​jī​duì zài dí​jūn fáng​xiàn shàng dǎ​kāi le yī gè tū​pò​kǒu.

   The assault team opened a breach in the enemy's line of defense.

   Source: Dong Chinese Dictionary

2. 警方正试图从这些线索中寻找案件的突破口。

   jǐng​fāng zhèng shì​tú cóng zhè​xiē xiàn​suǒ zhōng xún​zhǎo àn​jiàn de tū​pò​kǒu.

   The police are trying to find a breakthrough in the case from these clues.

   Source: Dong Chinese Dictionary