Given a scientific passage and an answer, generate a question for the given answer.

Ex Input:
Passage: A metallic bond is the force of attraction between a positive metal ion and the valence electrons that surround itboth its own valence electrons and those of other ions of the same metal. The ions and electrons form a lattice-like structure. Only metals, such as the copper pictured in the Figure below , form metallic bonds. Answer: metallic bond

Ex Output:
What is the force of attraction between a positive metal ion and valence electrons?

Ex Input:
Passage: Today, scientists think that electrons truly are fundamental particles that cannot be broken down into smaller, simpler particles. They are a type of fundamental particles called leptons. Protons and neutrons, on the other hand, are no longer thought to be fundamental particles. Instead, they are now thought to consist of smaller, simpler particles of matter called quarks. Scientists theorize that leptons and quarks are held together by yet another type of fundamental particles called bosons. All three types of fundamental particlesleptons, quarks, and bosonsare described below. The following Figure below shows the variety of particles of each type. Answer: quarks

Ex Output:
What can protons and neutrons be broken down into?

Ex Input:
Passage: events in angiosperms are known as double fertilization (Figure 32.18). After fertilization is complete, no other sperm can enter. The fertilized ovule forms the seed, whereas the tissues of the ovary become the fruit, usually enveloping the seed. Answer: fruit

Ex Output:
After fertilization is complete, no other sperm can enter. the fertilized ovule forms the seed, whereas the tissues of the ovary become this?