Mr. Green didn’t understand ________ made his daughter so absent-minded this morning.
I found John _____ the desk, _____ his homework carefully.
We must set about _____ our lesson for the mid-term examination.
I can't understand _____ at that poor child.
–Can you spare me some time? –I'm afraid not. I have lots of letters _____.
The patient was warned _____ oily food after the operation.