A: Hi, Jack. Our speech competition about sports is coming.

B: Yean. I'm ready for it. ____?

A: I have no idea about it. Could you give me some good advice?

B: Well, that depends on your hobby. What's your favorite sport?

A: ____ .

B: Then, you should collect some information about football.

A: ____？

B: You can collect the information by reading newspapers and magazines. And you can also talk about the World Cup in Russia these days.

A: ____.Thank you very much.

B: ____.Bye.

A: Bye-bye.

轮船总是漂浮在水面上，一艘轮船从河里驶向大海，它受到的重力大小　____ 　（变大、变小、不变）；它受到的浮力大小　____ 　（变大、变小、不变）；它排开水的体积____ （变大、变小、不变）；轮船是下沉些还是上浮些　____ 　．

珠江三角洲成为我国民工最大接收地的主要原因是什么？

测得生活中一些液体的pH如下表：

小红在做“探究平面镜成像”的实验时，按要求回答下面问题：