He could have finished it on schedule, but ________ he fell behind.

Mrs Black isn’t in and I’ll have to ring ______. I would appreciate it if you ring _____ after 6 o'clock?  

A new study of HIV-infected people in Haiti indicates that starｔing treatment early could save many patients who might _______ die of AIDS.

 Process has been very smooth. ______, we are not confident that it will be completed on time.

Five firemen ________ escaped death when a staircase collapsed beneath their feet.