【正文】
Unit 1 The Changing World Topic 2 Which country has the largest population? one hundred and fifty yuan two thousand and eight Olympic Games millions of stars since(自從) 650 million years ago about one billion (1,000,000,000 ) years old two point two six () meters tall 1,000,000,000 one billion one point three four 100 one hundred 1,000 one thousand 1,000,000 one million 十億 點(diǎn) five hundred and fortythree point seven 1562 one thousand, five hundred and sixtytwo 6 004 001 six million, four thousand and one 7 198 764 502 seven billion, one hundred and niyeight million, seven hundred and sixtyfour thousand, five hundred and two one point three four 100 one hundred