In the environment area, there is a system ________ the waste is disposed of by using the principles of ecology.
Sam has been appointed _______ manager of the engineering department to take ____ place of George.
—Where is the shooting centre? —It is about 50 kilometres ______ the city of Beijing.
Though difficult, I ________ him find a job, which made him very pleased.
He was inspired to start again _________ he had failed.
–She looks very happy. She ________have passed the exam. --I guess so. It’s not difficult after all.