It is ______ to spend money in preventing illnesses by promoting healthy living rather than spending it trying to make people ______ after they are ill.
A big disaster took place in ________1960s when I was in ________teens.
Scientists have found no ________of life on Mars so far,though great efforts have made on the research.
A lot of people were made tired of the lecture which ________as long as four hours.
I have to amuse myself by looking after my 10-month baby since I have nothing important to work________these days.
It took the scientists seven days to________Takla Makan________“the sea of death”.