3 sentences

1. 所有的船只都必须遵守港口的信号灯。

   suǒ​yǒu de chuán​zhī dōu bì​xū zūn​shǒu gǎng​kǒu de xìn​hào​dēng.

   All vessels must obey the port's signal lights.

   Source: Dong Chinese Dictionary

2. 交通信号灯变红后，所有的车辆都保持静止。

   jiāo​tōng xìn​hào​dēng biàn hóng hòu, suǒ​yǒu de chē​liàng dōu bǎo​chí jìng​zhǐ.

   After the traffic light turned red, all the vehicles remained stationary.

   Source: Dong Chinese Dictionary

3. 他右转时忘了打信号灯。

   tā yòu​zhuǎn shí wàng le dǎ xìn​hào​dēng.

   He forgot to use his turn signal when turning right.

   Source: Dong Chinese Dictionary