Hiện tượng xảy ra khi ngâm một lá Cu vào dung dịch HCl dư là A.Cu tan dần. B.Cu từ màu đỏ chuyển thành chất rắn màu đen. C.tạo bọt khí. D.không có hiện tượng gì xảy ra.

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choose the word or phrase among A,B,C or D that best fits the blank space in the following pasage : Buckingham palace is the London residence of the British monarch . It is (1)......... in the West En section of the city. Buckingham Palace has four main wings that (2)........ a rectangle around a courtyard. It has 600 rooms .The grandest rooms are used for ceremonies and formal (3)....... events . The Queen's Gallery exhibits some of the royal collection of fine furniture and works of art.Behind the palace (4)......... a walled, 16- hectare garden . The palace was (5).......... a smaller residence built for the Duke of Buckingham in 1705 . In 1762, King George III bought the house. His son king George IV decided by 1819 that the British monarch should have a more (6).......... home . But arguments between the king and the British government over the design and cost of the building caused many delays . The work was not completed until the 1840s , over 10 years after the king 's death. Later monarchs added the east and south wings to the building . In the mid- 1820s, the residence was named Buckingham palace, in (7) ...... of its original owner . During World War II , the palace was hit (8)....... bombs and needed renovation. (1). A. located B. lying C. laid D. set (2). A. build B. make C. shape D.form (3) A. society B. social C. socialist D. socialism (4) A.lying B. lays C. laid D. lies (5) A. original B. originally C. origin D. former (6) A. impressive B. impressed C impression D. initial (7) A. remembering B. honor C. memory D. tribute (8) A. with B. due to C. because of D. by