1. Falta de materiales
2. Escuelas en malas condiciones
3. Maestros con poco compromiso
4. Falta de equipo electrónico para tomar clases (hoy en día)
Answer: There are several subgroups of mollusks, but only three major ones: - the Gastropods, made up mostly of snails and slugs. - the Bivalves, a group including clams, scallops, mussels, and oysters. - the Cephalopods, a group including octopus and squid.
Could you show a picture for your question..?
