(2) When learning mechanical vibration and mechanical waves, four students express their views on the phenomena they see, so that you can come from the perspective of physics.

A, solid can transmit mechanical waves, and transmit mechanical waves fastest, so A is correct;

B, can't March in a hurry, for fear of * * * vibration, amplitude, resulting in damage to the bridge. Similarly, when the train crosses the railway bridge, it needs to limit the speed, so B is correct;

C, Xiao Li said: My wooden door can't hear the sound in spring and summer, and it starts banging in autumn and winter, which is caused by the wind.

You can think of it this way: it is windy all the year round. If it is because of the wind, it will ring in spring and summer. So he was wrong.

In addition, in fact, when the weather is cold in winter, objects will vibrate more easily than "hard". In summer, objects are "soft" and are not easy to vibrate and sound. Imagine you take a stone, knock it on the floor and sponge it. So, c is wrong;

D. The vibration of leaves on the water shows that the vibration of particles is not transmitted with mechanical waves, so d is correct;

So I chose ABD.