#include<bits/stdc++.h>
#define ll long long
#define fr(i,j,k) for(register int i=j;i<=k;++i)
#define rf(i,j,k) for(register int i=j;i>=k;--i)
#define foredge(i,j) for(register int i=head[j];i;i=e[i].nxt)
#define pb push_back
#define Times printf("Time:%.3lf\n",clock()/CLOCKS_PER_SEC)
#define pii pair<int,int>
#define mk make_pair
using namespace std;
inline int read(){
	int x=0;
	bool f=0;
	char c=getchar();
	while(!isdigit(c)) f|=(c=='-'),c=getchar();
	while(isdigit(c)) x=(x<<3)+(x<<1)+(c^48),c=getchar();
	return f?-x:x;
}
inline void write(int x){
    if(x<0){putchar('-');x=-x;}
    if(x>9)write(x/10);
    putchar(x%10+'0');
}
inline void writeln(int x){write(x); puts("");}
inline void writepl(int x){write(x); putchar(' ');}
mt19937 rnd(chrono::steady_clock::now().time_since_epoch().count());
inline int randfind(int l,int r){return rnd()%(r-l+1)+l;}
const int Maxn=2e5+10;
vector<int> vc[Maxn];
int d[Maxn];
int n;
int rt,m;
int L[Maxn],R[Maxn];
int id[Maxn];
int leaf[Maxn],idx;
vector<pii> limit[Maxn];
vector<pii> ans;
inline void clear(){
    fr(i,1,n+1) d[i]=L[i]=R[i]=id[i]=leaf[i]=0,vector<int> ().swap(vc[i]);
}
inline void dfs(int x,int fa){
    L[x]=idx+1;
    for(auto y:vc[x]) if(y!=fa) dfs(y,x);
    if(d[x]==1) ++idx,leaf[idx]=x;
    R[x]=idx;
    if(L[x]==R[x]) return;
    // cout<<x<<' '<<L[x]<<' '<<R[x]<<endl;
    if((R[x]-L[x]+1)%2==0){
        limit[(R[x]+L[x])/2].pb(mk(L[x],R[x]));
        // printf("limit:%d\n",(L[x]+R[x])/2);
    }
    else {
        int s=L[x]-1+m-R[x];s/=2;
        s=(R[x]+s);if(s>m) s-=m;
        limit[s].pb(mk(L[x],R[x]));
        // printf("limit:%d\n",s);
    }
}
int lim,p[Maxn];
int T;
inline void Out(int x,int y){
    if(x>lim) x=rt;if(y>lim) y=rt;
    // if(n<=100) writepl(x),writeln(y);
    writepl(x),writeln(y);
}
inline bool cmp(int a,int b){return limit[a].size()<limit[b].size();}
inline void work0(int x){
    // if(T==38) cout<<x<<endl;
    int l=x,r=x+1;
    while(l!=r){
        if(l==0) l+=m;if(r==m+1) r=1;
        // cerr<<l<<' '<<r<<endl;
        // cout<<l<<' '<<r<<endl;
        Out(leaf[l],leaf[r]);
        --l;++r;if(l==0) l+=m;if(r==m+1) r=1;
    }Out(leaf[l],rt);
}
inline void work1(int x){
    int l=x,r=x+1;
    int lst=0;
    while(l!=r){
        if(l==0) l+=m;if(r==m+1) r=1;
        --l;++r;if(l==0) l+=m;if(r==m+1) r=1;
    }lst=l;l=x;r=x+1;
    // cout<<"*"<<lst<<endl;
    while(l!=r){
        if(l==0) l+=m;if(r==m+1) r=1;
        if(leaf[l]==limit[x].back().first){
            Out(leaf[l],leaf[lst]);
        }
        Out(leaf[l],leaf[r]);
        --l;++r;if(l==0) l+=m;if(r==m+1) r=1;
    }
}
inline void work(){
    idx=0;vector<pii> ().swap(ans);
    n=read();m=0;clear();lim=n;
    fr(i,1,n+1) vector<pii> ().swap(limit[i]);
    fr(i,1,n-1){
        int x,y;
        x=read();y=read();
        ++d[x],++d[y];
        vc[x].pb(y),vc[y].pb(x);
    }
    fr(i,1,n) if(d[i]==1) ++m;
    if(m==2){
        fr(i,1,n) if(d[i]==1) writepl(i);puts("");
        fr(i,1,n) if(d[i]==1) writepl(i);puts("");
        return;
    }
    fr(i,1,n) if(d[i]>2) rt=i;
    // rt=1;
    if(m%2==0){
        // cout<<"*"<<rt<<' '<<n+1<<endl;
        ++n;vc[n].pb(rt);vc[rt].pb(n);
        ++d[rt],++d[n];++m;
    }
    dfs(rt,0);
    // fr(i,1,n) if(d[i]==1) cout<<i<<' ';cout<<endl;
    fr(i,1,idx) p[i]=i;
    // fr(i,1,idx) cout<<leaf[i]<<' ';cout<<endl;
    sort(p+1,p+idx+1,cmp);
    // cout<<rt<<' '<<leaf[p[1]]<<' '<<limit[p[1]].size()<<endl;
    // cerr<<limit[p[1]].size()<<endl;
    assert(limit[p[1]].size()<=1);
    // ++T;if(T==38){
    //     fr(i,1,n) if(d[i]>1) cout<<d[i]<<' ';cout<<endl;
    //     fr(i,1,n) for(auto p:vc[i]) if(d[i]>1 && d[p]>1 && i<p) cout<<d[i]<<' '<<d[p]<<endl;
    //     int S=0;fr(i,1,n) S+=d[i];
    //     cout<<n<<' '<<S<<endl;
    //     cout<<d[rt]<<endl;
    //     cout<<"**"<<limit[p[1]].size()<<' '<<m<<endl;
    // }
    if(limit[p[1]].size()==0) work0(p[1]);
    else work1(p[1]);
}
inline void init(){
	int t=read();
	while(t--) work();
}
signed main(){
	// freopen("input.in","r",stdin);
	// freopen("output.out","w",stdout);
    init();
    // printf("\nTIME:%.3lf",(double)clock()/CLOCKS_PER_SEC);
	return 0;
}