Ensure the wound is free from dirt before ______ the bandage.
A. making
B. adding
C. tying
D. applying
It was difficult to treat patients because of a ______ of medicine.
A. deficient
B. shortage
C. lacking
D. missing
They had stopped for coffee in the children's section, ______ they suddenly heard a loud noise at the next table.
A. when
B. while
C. which
D. that