Cho PTHH: 2NH₃ + 3Cl₂ → 6HCl + N₂.

Kết luận nào dưới đây là đúng?

A. NH₃ là chất khử

B. NH₃ là chất oxi hóa

C. Cl₂ vừa oxi hóa vừa khử

D. Cl₂ là chất khử

Mark the letter A, B, C, or D on your answer sheet to indicate the sentence that best combines each pair of sentences in thefollowing questions.

She is so attractive. Many boys run after her.

A. So attractive is she many boys that run after her. 

B. So attractive is she that many boys run after her. 

C. So attractive she is that many boys run after her. 

D. So that attractive she is many boys that run after her.

tự làm đi dễ

hay,hấp dẫn

hay vãi nhồi

??????????????????????

1!+2.2!+3.3!+4.4!+5.5! 
=(2-1).1!+(3-1).2!+(4-1).3!+ 
(5-1).4!+(6-1).5! 
=2!-1!+3!-2!+4!-3!+5!-4!+6!-5! 
=6!-1!=720-1=719