Embedding into free topological vector spaces on compact metrizable spaces

For a Tychonoff space X, let V(X) be the free topological vector space over X. Denote by I, G, Q and S^k the closed unit interval, the Cantor space, the Hilbert cube Q=I^N and the k-dimensional unit sphere for k∈N, respectively. The main result is that V(R) can be embedded as a topological vector space in V(I). It is also shown that for a compact Hausdorff space K: (1) V(K) can be embedded in V(G) if and only if K is zero-dimensional and metrizable; (2) V(K) can be embedded in V(Q) if and only if K is metrizable; (3) V(S^k) can be embedded in V(I^k); (4) V(K) can be embedded in V(I) implies that K is finite-dimensional and metrizable.