下列离子在溶液中能大量共存，加入OH-能产生白色沉淀的是( ) _爱下问搜题

搜题请搜索小程序“爱下问搜题”

问题选择题

下列离子在溶液中能大量共存，加入OH^-能产生白色沉淀的是( )

A．Na⁺、K⁺、SO₄^2-、Cl^-

B．H⁺、Ca²⁺、CO₃^2-、SO₄^2-

C．K⁺、Mg²⁺、SO₄^2-、NO₃^-

D．H⁺、Na⁺、OH^-、SO₄^2-

答案

答案：C

阅读理解

Mike is a middle school student. He goes to school from Monday to
Friday. His home is about 5 miles from school. He usually walks to school.
It takes him 50 minutes to walk there. Nancy’s home is a little farther. It’s 20 miles from school. So she often takes the school bus. It takes her 15
minutes to get to school. Bob lives outside the city. It’s a town 30 miles
away from his school. He takes the subway. It takes him 8 minutes to get to
school by subway. He can have breakfast at home and then leave for the
subway station. He studies very hard.

Name	How	How far	How long
Mike	He(1)____________	It’s about 5 miles from school	(2)_________
(3)___	She takes the school bus	It’s(4)_________from school	15 minutes
Bob	He (5)__________	It’s 30 miles from his school	8 minutes

单项选择题

软件系统内部接口不包括______。

A．函数或方法接口
B．消息接口
C．类接口
D．局部变量