3 sentences

1. 对方球队的外线防守非常严密。

   duì​fāng qiú​duì de wài​xiàn fáng​shǒu fēi​cháng yán​mì.

   The opposing team's perimeter defense is very tight.

   Source: Dong Chinese Dictionary

2. 办公室的电话需要先拨0才能打通外线。

   bàn​gōng​shì de diàn​huà xū​yào xiān bō0 cái néng dǎ​tōng wài​xiàn.

   You need to dial 0 first to get an outside line on the office phone.

   Source: Dong Chinese Dictionary

3. 我军在这次战役中处于外线作战的有利地位。

   wǒ jūn zài zhè cì zhàn​yì zhōng chǔ​yú wài​xiàn zuò​zhàn de yǒu​lì dì​wèi.

   Our army was in a favorable position for exterior-line operations in this campaign.

   Source: Dong Chinese Dictionary