关于硬水的有关叙述正确的是     （  ）
①溶有较多钙镁离子的水是硬水 ②长期饮用硬水对人体健康不利 ③工业生产中都可以使用硬水 ④用硬水洗衣服，浪费肥皂且衣服洗不干净

（2015•成都）在图甲所示的电路中，R₁是定值电阻，R₂是规格为“20Ω 3A”的滑动变阻器，在电路中正确连接有一个电压表（图中未画出）．电源电压保持不变，闭合开关S，滑动变阻器的滑片P从b端滑向a端．当滑片P在最右端b处时，电压表示数如图乙所示；P在中点时，电流表的示数为0.8A，电压表示数如图丙所示（电压表选用的量程与乙图不同）．下列说法正确的是（　　）

根据对话内容，从方框中选择适当的句子补全对话（其中有两项是多余的）。

A: Linda, what do you usually do in your spare time?

B: ____ 

A: What's your favorite program?

B: ____ They make me happy and relax.

A: And which do you like better, sports shows or TV plays?

B: ____ TV plays often bring us moving stories. What about you, Amy?

A: ____ 

B: But I think it's hard to understand them sometimes.

A: ____ You'll have fun learning much knowledge.

阅读下面短文，从短文后所给的A、B、C、D四个选项中选出能填入相应空白处的最佳选项。

    This is an apple tree. There are many 1 on the tree. There are some 2under it, too. They are 3 happily. Under the tree I can 4 a boy and a girl. They're playing games with the dogs.  The boy is 5 a blue sweater and white shoes. He is Jim. He is 6 American student. He is 14. He 7 his school very much. The girl is Jim's sister, 8 name is Cindy. She is 11. She is in a yellow dress. Her shoes are yellow. 9 . Now they are standing here, they are waiting for their friends. They 10 to play games under the tree.