Q: What is the missing first step of the following process: - The stomach churns the food - With the aid of stomach acids - The food becomes a thick liquid - Is then passed to the small intestine.
A: Food leaves the esophagus and enters the stomach

Q: What is the missing first step of the following process: - Engines produce carbon dioxide - Living things produce waste - Waste decomposes - Decomposition produces methane - Water evaporates - Water vapor joins the atmosphere - Carbon dioxide, water vapor and methane are greenhouse gases -
A: People breathe and expel carbon dioxide

Q: What is the missing first step of the following process: - Over long periods of time rain can hit the limestone - And cause a acidic reaction - The limestone will slowly disintegrate - A large gap with be where the limestone was - Result in the cave.
A: Some of the rock in the ground is made of limestone

Q: What is the missing first step of the following process: - Release them into the air by process of sporulation - Spores are carried by the wind - Land in a hospitable growing environment - The spores germinate into the soil - The mushroom starts growing - The adult mushroom produce spores of its own to repeat the process.
A:
Adult mushrooms produce spores