According to the reaction between substances, hydrochloric acid can react four times and calcium hydroxide can react three times, so D and E are hydrochloric acid or calcium hydroxide, A can react with both D and E, A is sodium carbonate, C, B and F are carbon dioxide and iron oxide, and C can react with D and B. If D is calcium hydroxide, C is carbon dioxide, B is sodium hydroxide, E is hydrochloric acid and F is iron oxide, it is substituted into the block diagram.

A, metathesis reaction is the exchange of components between two compounds to generate two compounds, usually the reaction between acid, alkali and salt, so the reaction of carbon dioxide with sodium hydroxide and calcium hydroxide does not belong to metathesis reaction;

B, according to the analysis, C is carbon dioxide, and the solid of carbon dioxide is dry ice, which can be used for artificial rainfall;

The mixture of C, A and D is the reaction of sodium carbonate and calcium hydroxide. Because there is calcium carbonate in the product, there is precipitation after mixing A and D;

The mixture of D, B and C is the reaction of sodium hydroxide and carbon dioxide, and the products are sodium carbonate and water, so there is no obvious phenomenon in the reaction between them.

So choose BC