Now I am reading Groupes réductifs sur un corps local : I. Données radicielles valuées written by Bruhat and Tits in 1972. Let $\Phi$ be a root system, $G$ a group with a root data $(T,(U_{a},M_{a})_{a\in \Phi})$ of type $\Phi$, and $\varphi=(\varphi_{a}\colon U_{a}\longrightarrow \mathbb{R}\cup \{\infty\})$ a valuation of this root data. We denote by $A$ the equivalence class of $\varphi$. Then the bijective
$$
V\longrightarrow A;v\longmapsto \varphi+v
$$
provides $A$ with a structure of affine apartment. Bruhat and Tits defined an equivalence relation $\sim$ on $G\times A$ to be
$$
(g,x)\sim (h,y) \iff \exists n\in N \text{ such that } y=\nu(n)(x) \text{ and } g^{-1}hn\in P_{x},
$$
where all notations are the same in Bruhat-Tits paper. They called the quotient $X=G\times A/\sim$ the building of $G$. 
 My questions are that 
''Does the followings hold?
1. For any $x,y\in X$, there exists $g\in G$ such that $x,y\in gA$.
2. The action of $G$ on $X$ is strongly transitive.''

Since it is so called BUILDING, perhaps these are valid, but I would like to know the proof.