下列中学生的行为中,属于经济活动或经济行为的是( )
①“十一”小明为一家人外出旅游开支制定计划
②奶奶腰痛,小花帮她捶腰
③小剑骑自行车锻炼身体
④小芳去医院买药
A:①③
B:②③
C:②④
D:①④
下列实验操作正确的是( )
写出下列名词的复数形式。
①May I have some ____ (plum), please? Sure.
②There are seven ____ (boy) in the playground.
③The woman has two ____ (baby).
④How many ____ (peach)? There is only one.
⑤There are two ____ (library) in our school.
下列城市中,1月平均气温最低的是( )