A：1个
B：2个
C：3个
D：4个
300+500=____ 700+200=____ 800+600= ____
900-400=____ 1000-600=____ 1500-800=____
1400-900=____ 6000-5000=____ 900+800=____
—How many times _______ you _______ to Beijing this year?
—Three times.
-- What’s happening in the street?
-- A group _______ Green Peace are protesting against the summit.
