Practise negative statements with "to be": write the correct form of "to be" + "not" into the gaps. Example: They (to be + not) here. They are not here. Or: They aren't here.
Übe die verneinten Aussagen mit "to be": schreibe dir korrekte Form von "to be" + "not" in die Lücken. Beispiel: They (to be + not) here. Schreibe: They are not here. Oder: They aren't here.