(2) From the simple structural formula of esculetine, it can be seen that 1mol esculetine contains 2mol-OH and 1mol ester groups, and 1mol ester groups will generate 1mol carboxyl groups and phenolic hydroxyl groups, so 1mol esculetine can consume up to 4 mol NaOH, and esculetine contains. a、b、d；

(3) Cinnamyl alcohol can be obtained by hydrogenation on A, and cinnamic acid can be obtained by oxidation on A, so the functional group contained in A is aldehyde group, so the answer is:-ch = ch CHO;

(4) The essence of the esterification reaction of compound P under certain conditions is that carboxyl group loses hydroxyl group, and hydroxyl group loses hydrogen atom, that is, the chemical equation for producing esculenolide is +H2O, so the answer is+H2O;

(5) An ester of formic acid can undergo both silver mirror reaction and hydrolysis reaction, so the answer is: