Let's solve each expression:

1. (-1/2) - (2/3) + (-3/4) + (2/3)
   = -1/2 - 2/3 - 3/4 + 2/3
   = (-6/12) - (8/12) - (9/12) + (8/12)
   = (-6 - 8 - 9 + 8)/12
   = -15/12
   = -5/4

2. (2/11) - (3/8) + (4/11) - (6/11) - (5/8)
   = 2/11 - 3/8 + 4/11 - 6/11 - 5/8
   = (16/88) - (33/88) + (32/88) - (48/88) - (55/88)
   = (16 - 33 + 32 - 48 - 55)/88
   = -88/88
   = -1

3. (5/3) + (-7/6) - (2/3) + (1/6)
   = 5/3 - 7/6 - 2/3 + 1/6
   = (10/6) - (7/6) - (4/6) + (1/6)
   = (10 - 7 - 4 + 1)/6
   = 0/6
   = 0

4. (5/13) + (-5/7) + (-20/41) + (8/13) + (-21/41)
   = 5/13 - 5/7 - 20/41 + 8/13 - 21/41
   = (205/533) - (380/533) - (820/533) + (332/533) - (861/533)
   = (205 - 380 - 820 + 332 - 861)/533
   = -1524/533

5. (-7/31) + (24/19) + (1/15) + (7/31) + (-5/19)
   = -7/31 + 24/19 + 1/15 + 7/31 - 5/19
   = (-133/589) + (1176/589) + (39/589) + (133/589) - (155/589)
   = (1339/589)

6. ((-5/7) + (14/11)) + ((-11/14) + (14/-11))
   = (-5/7 + 14/11) + (-11/14 + 14/-11)
   = (-55/77 + 98/77) + (-77/154 - 154/77)
   = (43/77) + (-231/154)
   = (86/154) - (231/154)
   = -145/154

7. ((-12/5) + (5/12) + (1/4)) + ((7/5) + (-19/12) + (2/12)) - 2019^0
   = (-12/5 + 5/12 + 1/4) + (7/5 - 19/12 + 2/12) - 1
   = (-288/60 + 25/60 + 15/60) + (84/60 - 95/60 + 10/60) - 1
   = (-248/60) + (-1)
   = -413/60
   = -206.5

8. (2/7) - (3/8) + (11/7) - (-1/3) + (1/7) - (5/8)
   = 2/7 - 3/8 + 11/7 + 1/3 + 1/7 - 5/8
   = (32/56) - (21/56) + (88/56) + (56/168) + (24/168) - (105/168)
   = (32 - 21 + 88 + 56 + 24 - 105)/168
   = 74/168
   = 37/84