الخطوة 1اختر الخيار الصحيح
الخطوة 2أضف التدريبات التي تعجبك إلى المفضلة
Use warn about for specific things: They warned us about the bumps in the road.
We warn a person against a fault: His teacher warned him against breaking the rules.
Before a person we use with or in, before a thing we use at, about or by and before a gerund we use at; Keith is very disappointed at not winning the prize. We use that (optional before a new clause): I was disappointed (that) I didn't get an invitation.
In exchange for: He gave them his old car in exchange for a new one.