Аннотация:Generalizations of the theorems of Eberlein and Grothendieck on the precompactness of subsets of function spaces are considered: if is a countably compact space and is a space of continuous functions on in the topology of pointwise convergence, then any countably compact subspace of the space is precompact, that is, it has a compact closure. The paper provides an overview of the results on this topic. It is proved that if a pseudocompact X contains a dense Lindelöf \Sigma-space, then pseudocompact subspaces of the space C_p(X) are precompact. If X is the product Čech complete spaces, then bounded subsets of the space C_p(X) are precompact. Results on the continuity of separately continuous functions are also obtained.