HSK 4
Kòngzhìtǎ zhǐhuī fēijī ānquán jiàngluò.
The control tower directs planes to land safely.
HSK 6
Fēixíngyuán yǔ kòngzhìtǎ bǎochí liánxì.
The pilot maintains contact with the control tower.
HSK 7-9
Jīchǎng de kòngzhìtǎ quántiānhòu yùnzuò.
The airport's control tower operates around the clock.
