Cho sơ đồ: F₂ → + X HF → + Y SiF₄ . Các chất X, Y lần lượt là

A. H₂O, SiO₂

B. H₂, Si

C. HCl, SiCl₄

D. HBr, SiBr₄

Mark the letter A, B, C, or D on your answer sheet to indicate the word whose underlined part differs from the other three in pronunciation in each of the following questions.

A. stopped

B. washed

C. walked

D. warned