vì sao hiệu suất phát quang của đèn sợi đốt thấp

ngu rua cung ko biet

1+1=2

Read the following passage and mark the letter A, B, C or D on your answer to indicate the correct word or phrase that best fits each of the numbered blanks from 01 to 10.

Early writing and Alphabets

When people first began to write, they did not use an alphabet. Instead, they drew small pictures to (01) ______ the objects they were writing about. This was very slow because there was a different picture for (02) ______ word.

The Ancient Egyptians had a (03) ______ of picture writing that was (04) ______ hieroglyphics. The meaning of this writing was forgotten for a very long time but in 1799 some scientists (05) ______ a stone near Alexandria, in Egypt. The stone had been there for (06) ______ 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 (07) ______ picture writing. It (08) ______ of letters or symbols that represent a sound and each sound is just part of one word. The Phoenicians, (09) ______ lived about 3,000 years ago, developed the modern alphabets. It was later improved by the Roman’s and this alphabet is now used (10) ______ throughout the world

Điền vào ô 9

A. which                        

B. whose              

C. what                

D. who

Phương pháp nhận biết nào không đúng?

A. Để phân biệt được ancol isopropylic ta oxi hóa nhẹ mỗi chất rồi cho tác dụng với dd B. Để phân biệt metanol, metanal, axetilen ta cho các chất phản ứng với dung dịch

B. Để phân biệt metanol, metanal, axetilen ta cho các chất phản ứng với dung dịch  A g N O 3 / N H 3

C. Để phân biệt axit metanoic và axit etanoic ta cho phản ứng với Cu(OH)₂/NaOH

D. Để phân biệt benzen và toluen ta dùng dd Brom.

có vì thích ok baby

fwe dfw lku njkh ku jhki

Photpho trắng có cấu trúc mạng tinh thể

A. phân tử

B. nguyên tử

C. ion

D. polime