(1) sucrose and starch are hydrolyzed under the condition of dilute acid solution as catalyst, so) "certain conditions" means under the catalysis of dilute acid;

Therefore, the answer is: under the catalysis of dilute acid;

(2) Sucrose hydrolysate is glucose and fructose, starch hydrolysate is glucose, and glucose contains aldehyde group, which can react with newly produced copper oxide to produce brick-red precipitate, so the correct method is: first, add enough sodium hydroxide solution to the hydrolysate to neutralize excess acid to make the solution alkaline, and then add newly produced copper oxide to heat it. If brick red precipitate is generated, it means that aldehyde group exists, which means that starch and sucrose have been hydrolyzed;

So the answer is: firstly, add enough sodium hydroxide solution to the hydrolysate to neutralize excessive acid to make the solution alkaline, then add new copper hydroxide and heat it. If brick red precipitate is produced, it means that there are aldehyde groups, which means that starch and sucrose have been hydrolyzed.