Mary won’t keep slim ______she takes exercise every day.
—The exam was too difficult, wasn’t it? —Yes, I don’t think ______ could pass it.
People in the west make ____ a rule to buy Christmas presents for their relatives and friends.
--- What are you going to do tomorrow?--- I will go _____ with my friends on the lake.
You _____ practise the drums while the baby is sleeping.
After the new equipment was introduced,they produced ________machines this year as the year before.