```go
package main

import "fmt"

func main() {
    var t int
    fmt.Scan(&t)
    for i := 0; i < t; i++ {
        var a, b string
        fmt.Scan(&a, &b)
        firstA := a[0]
        firstB := b[0]
        newA := string(firstB) + a[1:]
        newB := string(firstA) + b[1:]
        fmt.Println(newA, newB)
    }
}
```