Tengo que comer ensalada. - I have to eat salad. Ella tiene que ir a caminar. - She has to go to walk.
We can also express obligation with hay + que + infinitive
Hay que comer ensalada. - It is necessary to eat salad. Hay que ir. - It is necessary to go.
Hay que estudiar para tener éxito. It is necessary to study to succeed.
Tengo que estudiar para tener éxito. I have to study to succeed.
Note! tener is a verb while hay is not. Tener must be conjugated.
Hay que obtener una visa. - It's necessary to obtain a visa. Hay que reservar una mesa. - It's necessary to reserve a table. Hay que practicar un idioma. - It's necessary to practice a language. Hay que estudiar. - It's necessary to study. Hay que leer. - It's necessary to read. Hay que observar las leyes. - It's necessary to obey the laws. Hay que estar muy alerta. - It's necessary to be very alert. Hay que cuidar a su bebé. - It's necessary to take care of your baby. Hay que ahorrar dinero. - It's necessary to save money. Hay que trabajar duro. - It's necessary to work hard.