minh hok lop 7  roi ban ơi

                    giai

Dat: S=2^2+2^3+2^4+....+2^100

Ta co: 2S=2^3+2^4+2^5+....+2^100+2^101

          2S=2^2+2^3+2^4+2^5+....+2^100+2^101-2^2

          2S=S+2^101-2^2

            S=2^101-2^2

vay S=2^101-2^2

100+0=100

ngu

Read the passage and choose the best answer.

Listed as a World Heritage Site in 1999, Hoi An is the (28) …………..……. main port of Viet Nam dating back to the 16th century. Today, most of its historic (29)………………….... have been preserved as landmarks. There are many things you can do there. For example, you can walk down the streets, (30) …………….……… by the atmosphere of times gone by. You should (31)............... the town during the full moon, when the shop owners turn off the lights and decorate the streets with candle lanterns. You can also take a sampan ride down the Song Do River, hunting traces of foreign traders such as the Japanese, Chinese, and Dutch who made Hoi An a centre of (32) ………………..……..in old Viet Nam.

A. structure

B. building

C. structures

D. buildings