The government __________ air quality in urban areas from level one to five : excellent,fairly good, slightly polluted, poor and dangerous.
Too much pressure from study leads to sleeplessness, which _______ increases the risk of forgetfulness.
______ which school was suitable for their son, the parents visited lots of different primary schools in the city.
When she is put in a situation _______ she has to make a remark on others, she usually changes the topic.
Lucy is a very optimistic girl. ______ she is faced with a difficulty, she always sees the bright side.
Late in the afternoon, they arrived at ______ small village ______ north of the West Hill.