I don't know whether my sister will come or not, but if she __________ , __________.
After the new technique was introduced, the factory produced______ tractors in 1998 as the year before.
_____ can you expect to get a pay rise.
Not only _____ polluted, but _____ crowded.
A middle-aged woman came _____ to the bus stop only_____ the bus had gone.
Only _____ as an interpreter _____ how important it was to practise speaking English.