Choose the best answer for the following sentence:
Many people __________________ of malaria, smallpox, before the process of
vaccination was invented in the 19th century.
vaccination was invented in the 19th century.
A.
have died
B.
had died
C.
would die
D.
were dying
Đáp án và lời giải
Đáp án:B
Lời giải:
had died