要不是

yàobushì
  1. if it were not for
  2. but for

CEDICT

Entry Composition

1 要不 yàobù
  1. otherwise
  2. or else
  3. how about...?
  4. either... (or...)
=2 是 shì
  1. to be (followed by substantives only)
  2. correct; right; true
  3. (respectful acknowledgement of a command) very well
  4. (adverb for emphatic assertion)
=2 是 shì variant of 是 shì