守 + 在 + Place
守 (shǒu) is a verb meaning "to guard," "to keep watch over," or "to wait by." It implies staying in one place to protect or wait for something, and appears in well-known idioms like 守株待兔 (to wait idly for opportunities).
士兵们日夜守在边境线上。
Shìbīngmen rìyè shǒu zài biānjìng xiàn shàng.
The soldiers guard the border day and night.
奶奶一直守在电话旁边等你的消息。
Nǎinai yìzhí shǒu zài diànhuà pángbiān děng nǐ de xiāoxi.
Grandma has been waiting by the phone for your news.
他答应守住这个秘密,绝不告诉别人。
Tā dāying shǒu zhù zhège mìmì, jué bù gàosu biérén.
He promised to keep this secret and never tell anyone.