```go
package main

import "fmt"

func main() {
	var t int
	fmt.Scan(&t)
	for i := 0; i < t; i++ {
		var n int
		fmt.Scan(&n)
		if n%2 != 0 {
			fmt.Println("NO")
		} else {
			fmt.Println("YES")
			k := n / 2
			var s string
			for i := 1; i <= k; i++ {
				var ch byte
				if i%2 == 1 {
					ch = 'A'
				} else {
					ch = 'B'
				}
				s += string(rune(ch)) + string(rune(ch))
			}
			fmt.Println(s)
		}
	}
}
```