Question

fill in the blanks .Use should, have to,must, needn`t,can.
1.Nobody answers the phone.They....be out. 
2.The watter was clean.You...have boiled it .
3. we...call the doctor.
4. ...you do me a favout.
5.You ... drive more carefully.

Answer 1

1. Must
2. Needn't
3. Should
4. Can
5. Have to