Which phosphorus, a substance _____ in matches, is so flammable that it burst into flame upon contact with the air.

If you want a flat in the centre of the city, you have to pay through the _____ for it.

If he _____ harder, he would have passed the exam.

Among bees _____ a highly elaborate form of communication.

My grandmother was a lovely person who_____ pleasure from helping others.

As they came under heavy fire, the captain ordered his men to _____.

My father has decided to _____ a beard to cover a small scar he has on his chin.

Mark the letter A, B, C, or D on your answer sheet to indicate the underlined part that needs correction in each of the following questions.
People live (A) in big cities (B) often have trouble (C) making friends (D).