Làm vài giải thích ạ 
----- Nội dung dịch tự động từ ảnh -----
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.

19. A. in
We are tired ___ waiting the weather ___ to clear.
B. are
C. to
D. writing

20. A recent study of 2000 species of plants and animals have suggested an answer to this question.
B. have
C. to
D. species