科技小组的同学设计了如图甲所示的恒温水箱温控电路（设环境温度不高于20℃），由工作电路和控制电路组成．工作电路中的电热器上标有“220V2000W”的字样；控制电路中热敏电阻Rt作为感应器探测水温，置于恒温水箱内，其阻值随温度变化的关系如图乙所示，R1为滑动变阻器．电磁铁产生的吸引力F与控制电路中电流I的关系如图丙所示，衔铁只有在不小于3N吸引力的作用下才能被吸下．闭合开关S（不计继电器线圈的电阻）．则正确的是（     ）

阅读理解

Hi，HanLi，

    got some good news to tell you．One of our old friends，Zhao Yan，is going to visit us at the weekend．Do you remember her?She has a round face and two big eyes．She lives with her parents in Tianjin and is coming to see us．Lisa is her English name．I've got two photos of Zhao Yan. In one photo，she is playing basketball．That' my favourite sport.In the other one,she is drinking pear juice.It is her favourite.

    Let's have a picnic near a lake on Saturday．Of course，we can go boating too．Maybe you'd like to swim in it．Remember to catch the fish when you see them in the water．I'm going to meet Zhao Yan at the airport on Saturday morning．And we can meet near the lake at about eleven o'clock．You may come by bus．Remember to get off the bus at Lake Stop．

Yours，

WuTong

根据材料内容选择最佳答案。

He suggested _____ a conference and it suggested he _____ in our project.

下列是一元一次方程的是（     ）

下列有关群落的空间结构的说法中正确的是（    ）