_____ these experiments were successfully completed would we think of going into humans.
If you know the two sentences are different _____ each other, you had better tell us the difference _____ them.
_____ Mr. Brown’s anger, it was his own son who didn’t agree with him.
_______his writing,the writer forgot to have his lunch.
It is human activities on the earth that are to ______global warming.
After staying in hospital for long, the patient was advised to go to the seaside to _____ his health.