#!/usr/bin/env python
import os
import sys
from io import BytesIO, IOBase

def solve(i):
    n, m = inLst()
    A = inLst()
    queries = inLst()
    prefix = [A[0]]
    for i in range(1, n):
        prefix.append(prefix[-1] + A[i])
    for i in range(1, n):
        prefix[i] = max(prefix[i], prefix[i-1])
    cycleSum = sum(A)

    def querySolver(target):
        lo = 0
        hi = len(prefix)
        while lo < hi:
            mid = lo + hi >> 1
            if prefix[mid] < target:
                lo = mid + 1
            else:
                hi = mid
        if lo < len(prefix) and prefix[lo] >= target:
            return lo
        elif cycleSum <= 0:
            return -1
        else:
            numCycles, rem = divmod(target, cycleSum)
            if rem == 0:
                return numCycles * n - 1
            target -= numCycles * cycleSum
            lo = 0
            hi = len(prefix)
            while lo < hi:
                mid = lo + hi >> 1
                if prefix[mid] < target:
                    lo = mid + 1
                else:
                    hi = mid
            return numCycles * n + lo

    return [querySolver(q) for q in queries]


def main():
    for i in range(inInt()):
        outLst(solve(i))


# region fastio

BUFSIZE = 8192


class FastIO(IOBase):
    newlines = 0

    def __init__(self, file):
        self._fd = file.fileno()
        self.buffer = BytesIO()
        self.writable = "x" in file.mode or "r" not in file.mode
        self.write = self.buffer.write if self.writable else None

    def read(self):
        while True:
            b = os.read(self._fd, max(os.fstat(self._fd).st_size, BUFSIZE))
            if not b:
                break
            ptr = self.buffer.tell()
            self.buffer.seek(0, 2), self.buffer.write(b), self.buffer.seek(ptr)
        self.newlines = 0
        return self.buffer.read()

    def readline(self):
        while self.newlines == 0:
            b = os.read(self._fd, max(os.fstat(self._fd).st_size, BUFSIZE))
            self.newlines = b.count(b"\n") + (not b)
            ptr = self.buffer.tell()
            self.buffer.seek(0, 2), self.buffer.write(b), self.buffer.seek(ptr)
        self.newlines -= 1
        return self.buffer.readline()

    def flush(self):
        if self.writable:
            os.write(self._fd, self.buffer.getvalue())
            self.buffer.truncate(0), self.buffer.seek(0)


class IOWrapper(IOBase):
    def __init__(self, file):
        self.buffer = FastIO(file)
        self.flush = self.buffer.flush
        self.writable = self.buffer.writable
        self.write = lambda s: self.buffer.write(s.encode("ascii"))
        self.read = lambda: self.buffer.read().decode("ascii")
        self.readline = lambda: self.buffer.readline().decode("ascii")


sys.stdin, sys.stdout = IOWrapper(sys.stdin), IOWrapper(sys.stdout)
input = lambda: sys.stdin.readline().rstrip("\r\n")

############ ---- Input Functions ---- ############
# Integer inputs
inInt = lambda: int(input())
# List inputs
inLst = lambda: list(map(int,input().split()))
# String input (transforms into list of chars)
inStr = lambda: list(input())
# Space separated integer variable inputs
inVar = lambda: map(int,input().split())

########### ---- Output Functions ---- ############
# Print integer
outInt = lambda n: sys.stdout.write(str(n) + "\n")
# Print integer list 
outLst = lambda lst: sys.stdout.write(" ".join(map(str,lst)) + "\n")
# Print string
outStr = lambda s: sys.stdout.write("".join(s) + "\n")

# endregion

if __name__ == "__main__":
    main()
