- Complete the sentences with the correct form of have to. - Hoàn thành các câu với hình thức đúng của have to.. - have to 2. - have to 3. - had to, don't have to 5. - have to 6. - have to Câu 4. - Shouldn’t 4 Should. - Has to 7 Have to. - Shouldn’t 8 Should. - Have 11 Have to. - You don't have to tip in Vietnam.