cho tam giác ABC trên cạnh AB lấy điểm D sao cho BD = 2 AD. gọi E là một điểm thuộc cạnh AC sao cho CE = 3AE. BE cắt CD tại M. Tia AM cắt BC tại F khi đó dt BDF/ dt ABC =?

Nung 24,2 gam hỗn hợp X gồm sắt II hidroxit và sắt III hidroxit thu được 18,6 gam hỗn hợp Y gồm sắt II oxit và sắt III oxit . Phản ứng xảy ra theo sơ đồ: Bazơ không tan ot oxit + nước Em hãy tính khối lượng mỗi chất trong X và khối lượng mỗi chất trong Y

Read the following passage and mark the letter A, B, C or D to indicate the correct word or phrase that best fits each of the numbered blanks from 31 to 35.

Early writing and Alphabets

     When people first began to write, they did not use an alphabet. Instead, they drew small pictures to (31) _______ the objects they were writing about. This was very slow because there was a different picture for every word.

     The Ancient Egyptians had a (32) _______of picture writing that was called hieroglyphics. The meaning of this writing was forgotten for a very long time but in 1799 some scientists (33) _______ a stone near Alexandria, in Egypt. The stone had been there for over a thousand years. It had both Greek and hieroglyphics on it and researchers were finally able to understand what the hieroglyphics meant.

     An alphabet is quite different from picture writing. It (34) _______of letters or symbols that represent a sound and each sound is just part of one word. The Phoenicians, who lived about 3,000 years ago, developed the modern alphabets. It was later improved by the Roman's and this alphabet is now used (35) _______ throughout the world.

Điền vào ô số 33

A. discovered

B. realized

C. delivered 

D. invented