使用(),严禁使用不负责任的、歧视性和侮辱性的语言.
参考答案:文明用语
Mrs. Obama introduced the Let’s Move _______ yesterday. Its goal is to reduce children obesity(肥胖) today and in the future.
A.challenge
B.battle
C.campaign
D.behavior
把(a+b)当作一个因式,合并7(a+b)-3(a+b)+2(a+b)=( )