In communication, a smile is usually ______ strong sign of ______ friendly and open attitude.
The fresh air on the farm ___ him ___ his headache.
Once ___ light, the film will be damaged and get useless.
The patient has been ___ by nurses night and day since the operation.
You can have your computer repaired by John, which is ___ he is ___.
After a series of researches, they finally ___ that the pollution was the leading factor contributing to the death of the creatures in the river.