这套防御体系能拦截多数低空目标,但成本极高。Zhè tào fángyù tǐxì néng lánjié duōshù dīkōng mùbiāo, dàn chéngběn jí gāo.This defence system can intercept most low-altitude targets, but its cost is extremely high.
城墙高大结实,在古代起着重要的防御作用。Chéngqiáng gāodà jiēshi, zài gǔdài qǐ zhe zhòngyào de fángyù zuòyòng.The city wall was tall and solid and played an important defensive role in ancient times.
人的免疫系统是身体最重要的防御力量。Rén de miǎnyì xìtǒng shì shēntǐ zuì zhòngyào de fángyù lìliàng.The human immune system is the body's most important defensive force.